Budding hobbyists almost have it too easy these days, what with all the ready-made components, Mindstorms and Arduino boards, but there's still a couple of folks out there kicking it old-school... and printing transistors at home. Yes, that's a RepRap 3D printer you see there, with a MakerBot Unicorn pen head, depositing tiny dots of silver ink to form intricate rows of tiny electrodes. Sadly, the printer doesn't currently automate the entire process, as you'll also need to separately apply a dielectric material and a host of chemicals to get a working field effect transistor from scratch, but once the basic process is perfected the possibilities, as they say, are endless. Now if you'll excuse us, we've got a hot date with some vacuum tubes. Find the basic formula for DIY transistors at our source link.