I just stumbled across a YouTube video of some university students making a
simple MEMS device. Granted, it would require some setup and care to do
well, but it's a little surprising how totally doable nearly every step
appears for a not-completely-obsessed hobbyist. Granted, they don't show
every step, and the plasma step in particular would probably take some
work. But most of it seems to be things like vacuum pumps, spin-coating,
acid etching, and wearing lots of Tyvek. ;)
So then 10 seconds of Googling later, I came across the "Home CMOS"
project. Not sure how far they have to go before they have something
working, but I thought it was cool (check out their nyanotech):
People with weird hobbies are awesome.