Kids, MakerBot, LEGO Digital Designer, and peace education
Paul D. Fernhout
Makerbot:
http://groups.google.com/group/openmanufacturing/browse_thread/thread/34ba3d28a08f83e6
Here is something my kid and I watched yesterday about someone using a
MakerBot and CAD software to repair a lamp in a kitchen:
"YouTube - Better Living With MakerBot - Episode 1: Kitchen Lamp"
http://www.youtube.com/watch?v=LBzyZSVK_Gs
And I see now there is a second (longer) episode:
"Better Living with MakerBot - Episode 2: The Wall Socket "
http://www.youtube.com/watch?v=W9tnqHS2vFo
Also interesting as a general idea for kids:
"YouTube - Makerbot Toy Car"
http://www.youtube.com/watch?v=eWW5DFWcvhE
I've been explaining to my kid that a Makerbot is essentially the same
as this Lego 3D printer that prints stuff out of LEGO,
http://battlebricks.com/makerlegobot/
Except MakerBot works at a smaller scale (with drops of plastic instead
of Lego bricks). Of course, now there is some interest in getting a
$1000 Makerbot after seeing those videos, so maybe that was a bad idea? :-)
BTW, the latest version (version 4) of the free-as-in-beer LEGO Digital
Designer that we just installed has starter modules at three levels of
detail, using more and smaller bricks in the more detailed designs,
which made that easier to explain.
http://ldd.lego.com/
The in-place upgrade of LDD from version 3 went bad and we had to
reinstall, but it could still read all our old files. I'd really
recommend anyone interested in open manufacturing and education try LEGO
Digital Designer just to see what the state-of-the-art is in CAD
software designed for kids.
Somehow over the last three years or so (homeschooling/unschooling),
without me doing very much "teaching" about CAD (other than reading a
few Lego Digital Designer dialog boxes here and there for LDD after
demonstrating it), and even without my kid even being an extensive
reader yet, my young kid has become a "CAD-literate" user of 3D CAD
software as represented by LDD. Even if LDD as a CAD tool is "just"
about LEGO, it's still about "CAD". That seems like an important 21st
century skill. My kid has also been starting with some 3D home design
software now, just for fun.
And there is probably little in the "standards" for my state's education
policies for K-6 about being "CAD literate", even if there are endless
things one can and does learn about math, science, technology, and even
textual reading through LEGO. As I see it, there are many forms of
literary in this world (including literacy about nature or about reading
faces, for example).
One advantage of LEGO Digital Designer or a kid is it is easier to find
the parts you want than pawing through a bunch of bins. And you don't
have to sort part after you are done with your model. Though too much
computer time isn't good for kids, especially if they don't get exercise
and vitamin D or enough time around other people. One disadvantage for
the parent is it keeps the kid thinking about buying LEGO (including all
the parts for a model just designed, which we have done a couple of
times in the past).
This also goes to show that LEGO, which makes many violence-related
models at this point (Star Wars is a big seller), also makes some great
things (even for free) like LEGO Digital Designer. Such a mix of choices
that can be hard for a child or even parent to navigate.
Coincidentally, we just had an unfortunate experience watching the old
Speed Racer cartoon for the first time yesterday, where the very first
thing we watched unfortunately had Speed in the first few minutes
involved in someone' death through a fall from a rooftop, even though,
in general Speed is always trying to be good and helpful (if, I now see,
often in a violent or competitive way). If we had seen that death in
real life, how traumatic would it have been? We did not watch much more
of that episode. And feeling life is like that all the time could lead
to anxiety. Serves me right for not previewing it. There are probably
better episodes, even given what is said here:
http://www.military.com/entertainment/movies/movie-news/60s-cartoons-led-to-speed-racer-film
"Back in the `60s and `70s, though, few could imagine that Hollywood
would ever pin hopes on a live-action take on what then seemed to be
strange, disturbingly violent Japanese cartoons that were totally at
odds with American sensibilities."
Anyway, I guess that, in general, watching a lot of MakerBot or LEGO
videos may be a bit more healthy and wholesome than watching a lot of
Speed Racer in that sense, even if Speed Racer always means well? :-)
Even, or especially, if engineers disagree sometimes and need to learn
to deal with that? :-) Without denying conflict does need to be dealt
with, I can expect that in the same way that having a house full of
whole foods is going to probably lead to a healthier kid than a house
full of junky food, if we provide kid with lots of opportunity for time
with things like Makerbot videos, LEGO Digital Designer, and so on
(including chances for sharing via YouTube and in person and doing
hands-on stuff with actual Makerbots and LEGO and so on), I'd expect
we'll probably get more productive and more cooperative kids than ones
raised on junky TV where violence and competition is often the main way
to solve problems. It's not necessarily that watching violent TV leads
to violence (people can dispute that) as much as watching violent media
takes up the time you might be using to learn about alternative ways of
solving problems.
A lot of old TV is very worth watching, of course, like for example
SeaLab 2020 (sad you can only find the Sealab 2021 satire), the Electric
Company, and the New Zoo Review, and recent TV probably has good stuff
too, of course. Even Speed Racer may have redeeming qualities
(especially if used as a springboard to discussions, at least for older
kids). Still, it's a challenge to teach kids how to deal morally and
effectively with conflict without glorifying it. I have a longer essay
related to this general theme based on a related book called "The War
Play Dilemma" here:
http://www.pdfernhout.net/the-war-play-dilemma.html
Other related stuff by someone else:
"Educating for a Peaceful World" by Morton Deutsch
http://www.forums.alliance21.org/d_read/pax/articles/Deutsch.htm
Anyway, for those interested in teaching for a peaceful world, getting
kids making stuff, especially working together with others in a
cooperative way, has got to be a good thing. I think that idea of
MakerBot used for peace education may provide yet another on ramp for
open manufacturing, another justification for its use in educational
settings like many schools claim to be.
Of course, you know kids are going to print out parts for guns or
whatever with MakerBot (I made parts for a rubber band gun in shop class
as a kid). Even for LEGO, we have this book and I built toy guns out of
building blocks as a kid (Star Trek phasers, etc.):
"Forbidden Lego: Build the Models Your Parents Warned You Against! "
http://www.amazon.com/Forbidden-Lego-Models-Parents-Against/dp/1593271379
But overall, one can hope MakerBot as well as LEGO is going to be a good
thing for education, especially with a good context around it.
I can wonder if it might be interesting if MakerBot could print out
solid versions of some restricted subset of LEGO models? I don't mean
printing LEGO-compatible bricks (which does not seem to go well)
http://makerblock.com/2010/01/makerbot-and-legos/
but just using the same construction techniques as LDD to build a
MakerBot-friendly model?
http://en.wikipedia.org/wiki/MLCAD
I'm not saying that is the optimum way to design for MakerBot, just that
it is an interesting way, and builds on what many kids are already
learning. Maybe someone has done this already, going from a model
designed as a collection of individual LEGO bricks to MakerBot output of
an entire solid model?
--Paul Fernhout
http://www.pdfernhout.net/
====
The biggest challenge of the 21st century is the irony of technologies
of abundance in the hands of those thinking in terms of scarcity.
Bryan Bishop
> Anyway, I guess that, in general, watching a lot of MakerBot or LEGO videos
> may be a bit more healthy
You may also be interested in my "machine porn" playlist:
http://www.youtube.com/user/kanzure#grid/user/0EB93E6E02E5CF17
like:
5-axis cnc machine
http://www.youtube.com/watch?v=RnIvhlKT7SY
RND Automation & Engineering
http://www.youtube.com/watch?v=8s3IlIE4Yuk
Kuka Robot Group
http://www.youtube.com/watch?v=TGCiJvKaZtQ
Mattress factory automation
http://www.youtube.com/watch?v=wbDwUWGvwq4
Paul D. Fernhout
> On Sat, Oct 30, 2010 at 9:13 AM, Paul D. Fernhout wrote:
>> Anyway, I guess that, in general, watching a lot of MakerBot or LEGO videos
>> may be a bit more healthy
>
> You may also be interested in my "machine porn" playlist:
> http://www.youtube.com/user/kanzure#grid/user/0EB93E6E02E5CF17
>
> like:
>
> 5-axis cnc machine
> http://www.youtube.com/watch?v=RnIvhlKT7SY
>
> http://www.youtube.com/watch?v=8s3IlIE4Yuk
>
> Kuka Robot Group
> http://www.youtube.com/watch?v=TGCiJvKaZtQ
>
> Mattress factory automation
> http://www.youtube.com/watch?v=wbDwUWGvwq4
Thanks.
Beats hanging out with gloomsters. :-) Like this review of Catton's
latest book on how we are all doomed (even if socially, I won't say he
does not have a point about some things being messed up).
"Bottleneck: Humanity's Impending Impasse, by William R. Catton, Jr."
http://www.theoildrum.com/node/5954
"In the sequel, Bottleneck: Humanity's Impending Impasse, Xlibris
Corporation, [Catton] drops the part about we can evade the worst. The
subtitle says it all. Now he concludes that it is already too late to
mend our ways and somehow avoid the collapse of civilization. ..."
But even at that site, there is some optimistic sanity (even if they may
be confusing Marx and Malthus a bit, although I think I know what they
are trying to get at?):
http://www.theoildrum.com/node/5954#comment-563308
"The only way to interpret this is if you accept the basic assumption of
Marxism - that available resources are constrained in a fixed manner,
and only in a fixed manner.
And that efficiency improvements don't exist. That new technologies
don't exist. That we and all methods we currently use are final, perfect
and sacred.
If you believe this to be true, despite overwhelming evidence to the
contrary, you will end up as a Marxist. For over 4000 years you will
find these sort of arguments in just about every civilization, and every
time much more damage was done by listening to them than by ignoring
them. Nearly every time (yes - nearly) ignoring those limits brought
salvation. New technology, new energy sources, new methods of working,
or simply emigrating brought respite.
Savings never brought respite, even in the cases were the doomsayers
were right, and the natural resources were finished.
If the book is true, 90% of humans (at least) have to die. Do tell,
on this site, who's volunteering ?"
Here is a graph I look at every once in a while about solar prices.
There has been a big drop in PV cost over the last couple of years with
no end in sight:
http://www.solarbuzz.com/Moduleprices.htm
Installed cost of electricity (without subsidy?) over the past decade
has dropped from around US$0.40 per killowatt-hour to about US$0.32:
http://www.solarbuzz.com/solarprices.htm
Large industrial solar has gone from about US$0.21 to about US$0.17
during the same time.
More innovation in the works long term and prices should continue to
drop -- just some random recent examples:
http://inhabitat.com/2010/08/04/super-cheap-solar-cells-switch-gold-for-nickel/
http://inhabitat.com/2010/09/03/new-black-silicon-solar-cells-are-cheap-and-absorb-more-sun/
http://inhabitat.com/2010/10/29/thermo-chemical-solar-energy-is-efficient-and-indefinitely-storable/
http://www.techeye.net/business/us-to-build-6bn-solar-farm-in-californian-desert
Anyway, there is something to be said for encouraging technical
enthusiasm in a next generation. :-)
Even if our technology sometimes ironically does us in. :-(
Catton is not all wrong though. For example, perhaps ironically we may
indeed do ourselves in using solar-powered nuclear missiles to fight
over oil or other scarcity misperceptions. I agree with Catton that,
despite there being plenty of technical fixes (where we disagree,
because he denies them), that we as a society may indeed decide to
pursue a form of ideologically-driven collective suicide -- like
choosing to do ourselves in in various ways fighting over (mis)perceived
scarcity (or the market-with-externalities-ignored as God?), ironically,
probably using solar-powered nuclear missiles to fight over oil etc..
The USA has solar panels for missile silos for a while, but it looks
like others are following suit in various ways (although I question if
those missiles really are solar powered other than keeping the batteries
charged):
"Militants go green,use Solar powered missiles"
http://ibnlive.in.com/news/jk-police-recover-solarpowered-missiles/117019-3.html?from=tn
http://www.defence.pk/forums/kashmir-war/60300-militants-go-green-use-solar-powered-missiles.html
"Srinagar: Jammu and Kashmir Police's special operations group have
recovered a cache of sophisticated missiles from a terrorist hideout in
the state. The seizure of two sophisticated missiles which can be
charged using solar power has sent the alarm bells ringing in the
security establishment. The missiles were positioned for an offensive
action in the Gujjarpati forest area of Kupwara district. The missiles
can be fired without any human assistance as the solar panel on each
missile is programmed to trap sun rays which can be converted into
thermal energy to propel the weapon. Police believe that the missiles
could be of either Chinese or Russian make."
What a different mindset in those missile makers compared to say over at
things cited by inhabitat, where engineers and activists work to solve
problems, not make more of them. Example:
http://inhabitat.com/2010/10/29/nine-squarefoo-cabin-is-a-fully-functional-frugal-micro-home/
"Nine is the magic number for the amazingly small, but functional mini
cabin proposed by Michael Janzen. Just long enough to sleep in and tall
enough to stand in, the cabin is placed on a lightweight wheeled frame
making it easily transportable. Meeting modern standards for living, on
the interior one can find all the things they need to get through the
day—a tiny kitchen, shower, toilet, a place to sleep and even a porch.
The Nine Tiny Feet Cabin does it all in a singular sustainable design,
while simultaneously forgoing the need for any main grid hook ups. The
only trick? Tucking everything away when you don’t need it, and easily
accessing it when you do. ... While it may be just a bit too heavy to
pull with a bike, the cabin is a true portable living arrangement that
sufficiently answers the question of how to live frugally."
Related:
http://www.ninetinyfeet.com/
http://www.ninetinyfeet.com/2009/05/updated-design-mini-cabin/
Anyway, it's a very interesting creative exercise as making a
self-contained living space with minimal materials.
I think I'd rather live in this, though, even though it requires about
forty times more floor space: :-)
"Hong Kong architect turns shoebox apartment into 24 rooms "
http://www.youtube.com/watch?v=f-iFJ3ncIDo
"Find out how an award-winning Hong Kong architect has managed to
squeeze 24 rooms - including a home cinema and ''spa'' - into 344 square
feet of apartment space."
Thomas Fledrich
panel on each missile is programmed to trap sun rays which can be
converted into thermal energy to propel the weapon. "
That's bs. More than 10 kW is needed to produce just a few Newtons of
thrust. If this would work we would be seeing solar power driven
racing cars and passenger airplanes all over the place. Except if the
power would come from a laser beam rather than from the sun, but that
would be quite bulky and line of sight to the beam would have to be
maintained.
Paul D. Fernhout
I agree in general. Certainly the rocket could not fly just from solar
panel that were affixed on it, if any. As I mentioned, if solar panels
are involved, it is probably be to charge up electronics somehow (the
way the US uses solar panels to keep its land based nuclear arsenal
ready for fighting over oil etc.). But it is still ironic to have all
this advanced technology of abundance like solar power and use it to
fight over perceived "scarcity".
Still, just for reference about solar boats
"7 Awesome Solar Boats You Must See"
http://www.treehugger.com/files/2009/02/solar-boats-ships-pontoons-ferries-solar-panels.php
And for solar racers:
http://americansolarchallenge.org/events/asc2010/
And for manned solar planes, we've had them since 1981:
http://en.wikipedia.org/wiki/Solar_Challenger
A fancier one in the works:
http://www.solarimpulse.com/
"The adventurers of the last century were constantly pushing back the
limits of the impossible. Today, human and technological enquiry must go
on, aimed at improving the quality of life on our planet. In building
the first solar aircraft able to fly day and night, and piloting it
right round the world without fuel or pollution, Solar Impulse's
ambition is for the world of exploration and innovation to contribute to
the cause of renewable energies, to demonstrate the importance of the
new technologies for sustainable development, and to place dream and
emotion back at the heart of scientific adventure. ... [from elsewhere
on the site:] The Solar Impulse is a revolutionary concept that seeks to
push back the limits of our knowledge of materials, energy management
and man-machine interface. With its huge wingspan equal to that of an
Airbus A340, and its proportionally minimum weight, the HB-SIA prototype
presents construction features and an aerodynamic quality never
encountered until now. These place it in an as yet unexplored area of
flight. Carbon fibre structure, propulsion chain, flight
instrumentation, everything has been designed to save energy, to resist
the hostile conditions facing airplane and pilot at high altitudes and
to marry weight restraints and essential resistance. "
Of course, you said "all over the place", and it's true, they are not --
all these things remain oddities with various serious limitations.
Also, that is not to disagree with you about solar powered rocketry --
boats, cars, and airplanes are presumably much easier. Still, now that I
think about it, you could use a big solar panel, over the course of a
long time (as in weeks or months or even years), to produce hydrogen
from water that could be used as a rocket propellant for a very small
rocket (and those were small rockets). Also, we don't know how big the
solar array was (if any) that was involved. So, it is still
theoretically possible those rockets were "solar powered", even as I
still agree that is highly unlikely and probably the situation was
mistranslated or just misunderstood or something like that.
Related, just googling around (and getting myself on yet another
watchlist probably :-) I found this:
"Powering Water rockets with hydrogen combustion"
http://www.et.byu.edu/~wheeler/benchtop/hydropyro.php
"A few words of caution: water rockets pressurized with just air can be
dangerous. Water rockets pressurized by internal combustion can be
especially dangerous. The things described on this page look fun (and
they are!), but they require a great deal of caution. Whenever I launch
these rockets I exercise many safety precautions, the least of which is
the wearing of eye protection and staying at least 8 meters away from
the rocket while it is charged with fuel mixture."
It even has a video:
http://www.et.byu.edu/~wheeler/benchtop/vid/h2test.mpg
"The high gas temperature is the reason why the rocket glows briefly
during launch (the rocket is like a neon light). The hot gas does not
appear to harm the plastic rocket, probably because it doesn't stay
inside for very long. The ignition and launch produce a distinctive
�thunking� sound, but are no louder than an ordinary water-rocket
launch. The bottle returns to the earth slightly warm to the touch and
without the characteristic internal fog of conventional water rockets.
... My electrolysis unit, affectionately called �Mr. Splitter,� is
actually four cells in series and is designed to be operated off a
12-volt source�I use a 12-volt 7-amp-hr portable lead acid battery. The
unit draws about 10 amps of current, allowing it to generate about 0.5
liters/minute of fuel-gas mixture, composed of 2/3 hydrogen and 1/3
oxygen. The gas is carried to the rocket (mounted on the launcher) via
quarter-inch vinyl irrigation tubing. Building the electrolysis unit
took a great deal of painstaking work so that it operates safely and
efficiently."
At about US$2 per peak watt for a solar panel, and so $24 for 12-volt at
one amp, so $240 then for a solar panel to drive that splitter in peak
sun (and presumably it could just run during peak sun, so, in a sunny
place, maybe six hours a day). The only question is, how much hydrogen
does a model rocket of a certain weight need?
According to here:
http://exploration.grc.nasa.gov/education/rocket/rktenglab.html
"A C6-4 has an average thrust of 6 Newtons. The average thrust times the
burn time of the engine is called the total impulse of the engine. The
letter gives the maximum total impulse of that class of engine. An "A"
engine has a maximum impulse of 2.5 Newton-seconds,"
I have not been involved with a model rocket launch for a quarter
century, so I don't know what can do what, but to get 2.5
Newton-seconds, at your 10 kW for lets say about that thrust, you need
10kW for three seconds, or if creating hydrogen, about 100 watts for
about 300 seconds, or five minutes. Just to be in the ball park
(ignoring inefficiencies). So, I would guess that a biggish 200 watt
solar panel could fuel a small model rocket in, say, ten minutes? Am I
in the ballpark? Those rockets in the picture looked pretty big, and I
have no idea how far they might travel, but if they were going to fly a
couple miles, and they were heavy, they might have to be scaled up by a
factor of, say, 1000? So, it would take 10,000 minutes to produce the
fuel for one. Six hours of peak sun is 180 minutes. So, this would take
about 60 days, or about two months from one solar panel. Have ten
panels, and it could charge such a rocket in a week.
Obviously, there are probably simpler ways to go about obtaining
propellants for rockets than lugging solar panels out into remote areas,
given the panels themselves would weigh a lot more than propellant for a
small rocket, and they are fragile, and it would be likely a whole
jury-rigged system sitting around for days and exposed to the elements
would just blow up in your face.
Not, this is just for the sake of basic engineering analysis. I think
actually using such things in any violent way would be illegal,
counterproductive, immoral, and to be discouraged, for the reasons
outlined here:
"Social Movements and Strategic Nonviolence"
http://sociology.ucsc.edu/whorulesamerica/change/science_nonviolence.html
But, as a model rocketry fun thing to do, it does sound kind of neat for
the kind of person who likes dangerous fun and is not scared of
blindness, loss of limbs, and third degree burns.
Still, one can wonder if it is reasons like this why the CIA is hiring
machinists?
http://groups.google.com/group/openmanufacturing/msg/ae28e8971f8f9669?hl=en
Also, presumably solar panels could be detected by satellite
surveillance or Predator drones?
Of course, you don't need the solar panel if you have a working wall
outlet, so this is all just to explore the issue you raised of whether
such rockets (in theory) could be "solar powered".
Still, just like the fact that RC planes can now be guided by GPS
creates a whole range of security worries today, it looks like anyone
with a solar panel and some water and some electronics can make small
quantities of rocket fuel in the middle of nowhere if they are patient.
We need a better paradigm for rethinking our society to cope with
widespread abundance and technological capacity than "a war on terror"
-- given the capabilities any person is likely to have easy access to in
twenty to thirty years.
We need a culture that does not encourage people to use such
technologies to settle disputes in violent ways, but instead encourages
people to find common interests and work together with the tools of
abundance to build a better world. For example, while a lot of people in
Afghanistan are busy blowing each other up, essentially over reasons of
poverty, there is a fortune in minerals right beneath their feet, where
the same explosives used in killing could be used in mining:
"U.S. Identifies Vast Mineral Riches in Afghanistan"
http://www.nytimes.com/2010/06/14/world/asia/14minerals.html
"The United States has discovered nearly $1 trillion in untapped mineral
deposits in Afghanistan, far beyond any previously known reserves and
enough to fundamentally alter the Afghan economy and perhaps the Afghan
war itself, according to senior American government officials. "
More serious solar powered rockets going to orbit are still just dreams
though, even with a bit of reality testing:
http://www.al.t.u-tokyo.ac.jp/kimiya/kimiya3-E.html
"14. A Preliminary Study of Laser powered Launcher Performance
Katsurayama, H., Komurasaki, K., Arakawa, Y., Acta Astronautica, Vol.
65, (2009), pp. 1032-1041."
I saw a video of a very small such system being tested around 2001 as a
SSI conference (I don't remember who did it off hand, but it was a US lab).
Such systems would take very large ground or space installations to
collect the solar power of course. But the "rockets" would be little
more than a passenger or freight capsule, and so fairly light weight,
with a huge ground based laser firing pulses at the tail (with water or
an ablative material coming off the bottom as it was vaporized to
provide thrust).
But, probably, such rockets would be a lot more environmentally friendly
than any other kind of rocketry:
"Calculating Environmental Damage From Space Tourism Rockets"
http://science.slashdot.org/story/10/10/30/1310220/Calculating-Environmental-Damage-From-Space-Tourism-Rockets
A decade ago I was told by someone at NASA that they have a tough time
finding rocket scientists these days because kids are not allowed to
play with anything dangerous anymore. Of course, I can wonder how many
backyard casualties and distraught parents it takes to make one NASA
rocket scientist? Ten? One hundred? I'd certainly discourage my own kid
from playing with creating rocket fuel.
When I was in high school decades ago, the JETS club (engineering) had
been shut down a couple years before because the kids involved ordered
stuff to build a big rocket that (so the advisor said) in theory could
have hit an airplane (and so it became more of a computer club and we
did toothpick bridges etc.). Of course, it turns out computers are more
deadly because of vitamin D deficiency. :-)
http://www.vitamindcouncil.org/treatment.shtml
Not to mention other dangers related to computers.
http://freerangekids.wordpress.com/2010/02/26/school-uses-laptops-to-spy-on-kids-the-update-really-weird-update/
And we wonder why the USA can't "get it up" anymore. :-)
http://www.opennasa.com/2010/01/24/dreading-the-end-of-the-space-shuttle-program/
Contrast the ultra-safe US kid culture with what kids in the Middle East do:
http://bsimmons.wordpress.com/2007/01/29/never-too-young-to-bleed/
"Most participants make a small cut on their head, and then beat the
wound with their palm�or in this case a sword�to keep the wound open and
bleeding."
Related:
"Gever Tulley on 5 dangerous things for kids"
http://www.ted.com/talks/gever_tulley_on_5_dangerous_things_for_kids.html
Thomas Fledrich
panels. What I was referring to was that they would need higher power
output to replace hydrocarbon powered vehicles. Sure, if the cells are
used to recharge batteries (or convert sunlight to chemically stored
energy), then more applications would become practical (although the
military rockets the article was talking about are not the kind of I'm
looking forward to).
About the solar plane, that is an interesting project. It has already
completed a 7 days non-stop flight if I remember correctly. Such an
"eternal plane" will have many applications in telecommunication for
example.
For storing hydrogen in situ to propel a rocket, I might add it's not
that simple to store a lot of hydrogen. It requires either heavy
compression (several 100 bar or 1000 psi, at which point it is still
bulkier than simple gasoline), or cryogenic storage where it needs to
be cooled down to and kept at just a few Kelvins.
Having said that, hydrogen itself is an excellent rocket propellant,
especially if it is heated by an external process (focused beams etc.)
instead of being burned with oxygen. An SSTO (single stage to orbit)
would be possible with hydrogen, it can be brought to about 10 km/sec
exhaust velocity with current materials. Although the gigawatts of
beamed power required for ascent are still some time away, it would
already be an efficient propulsion for Earth-Moon travel. That's one
of the reasons why I'm so happy solar sail projects are finally
happening now
http://www.astrobio.net/exclusive/3604/setting-sail-in-the-sun
If we could use the sails to focus sunlight into a hydrogen filled
heat exchanger it would be a very lightweight and efficient means of
propulsion.
But to come back to the original topic, it's good to hear children are
so excited about MakerBots. They will learn a lot about combining the
virtual world of computer design with the actual results in the real
world when they make their own toy-models. I also think that, while
one should watch out for potential dangers, generally it would be at
least as safe to make plastic parts as what kids were building with
wood and stones before 3D printing was available.