The last time I recall there was a company that produced these things
(non-looped bicycle inner tubes) was maybe 10 years ago? Not very long.
I saw them posted around online on blogs, not in online or real-world
stores.... And I know I've seen the patents through the years come up
multiple times in searching for other stuff.
Last time I was browsing google patents I think I found about a dozen
bicycle tire patents that were for "an additional puncture protection
layer under the tread", and about a half-dozen more that were for
bicycle tires with "an additional puncture protection layer in the
sidewalls". Likewise, there is a few patents for "bicycle tires with
foldable beads"...
--I have noted that patents filed by large corporations (Trek, Giant,
Kenda ect) tend to be rather specific about their claims, while the
patents that are vague and broad are not usually filed by said large
corporations--
Also about every 5 years somebody gets a new patent on (bicycle) tire
scrapers.
And (almost) every modern bicycle saddle shape isn't modern... The one
exception being the Manta saddle, that I have yet to find anything
similar to in the wayback machine.
http://mantasaddle.co.uk/
Never owned or tried one. Looks intriguing, but it won't fit on any bike
I have nowadays. If I built a crank-forward-style copy I'd consider it.