Just for fun I put together a valve regen receiver using (mostly) components from Radionic construction sets. It runs off 12 volts for both filaments and HT. The output stage is in the style of a late 50s / early 60s hybrid valve/transistor car radio. Medium wave is fine but because of the lack of screening and fine tuning it's no fun to use at higher frequencies. I think I might add a metal front panel, fine tuning, some screening and maybe a ground plane and see how it goes. You can see it in more detail here:
https://www.youtube.com/watch?v=dwLHzm9sfcc