The amp is built into a little Radio Shack enclosure, has a push button switch for power, I think that came out of the reel to reel too actually. I used an old Fisher Price 9v adapter to power it, just broke open the case and mounted it inside with the amp. For some reason with all my shuffling and knocking it about it ended up putting out like 22 or so volts instead.... Not sure what's up with that. Gives the amp way more headroom and a better sound than a battery does though. I just drilled through the bottom of the enclosure into the speaker box to run the power wires down. That way the cord can come out of the bottom of the cabinet and not the amp enclosure, which I thought would look very stupid.
The amp itself is a little 1W headphone amp kit, the same kind I used for my reverb box. I added some shitty old caps and resistors to make sure it sounded less sterile, and that's that. Thing is actually really loud, and sounds pretty damn good. I like it a whole lot on theremin and synth, but the clean guitar is nice too.
Not going to beat an expensive boutique job, but it sounds weird and unique and I should be able to have some fun with it for recording. Spent less than $10 on it too.