I’ve just wired up a new case with a new-to-me PSU:
It’s a Bel Power Solutions HBB15-1.5-AG, a linear power supply capable of delivering 1.5 A each of ±12 V (or ±15 V). These seem to sell for $130 or so new, but I got a used one for $30 plus shipping on eBay.
120 V enters the case via a power inlet with a built in illuminated rocker switch and a built in fuse holder. You DO want a fuse in a setup like this, really. The inlet is covered on the inside with a blue plastic electrical box, and the 3 conductor cable runs to the PSU, entering through a hole in the orange 3d printed piece I made. That covers a slot on the side of the PSU, rendering the 120 V terminals inaccessible to wandering fingers. The open sides of the PSU are up against the wood side and front of the case, and it’s attached with long machine screws to a piece of sheet aluminum on the bottom. Earth ground connects to the PSU chassis. So everything 120 V is contained. ±12 V and ground wires go to a barrier strip nearby, and the bus boards (just one so far, second one later) connect to the other side.
I haven’t used this yet to power anything beyond two LEDs on the bus board and two LEDs in a power display module, so there could be issues I haven’t hit yet. I also haven’t examined the outputs on a scope yet. But it’s up and running at least, and Bel seems to have a good reputation so I have good hopes for this setup.