I'm not having any luck with this. I'd like to find a small enclosure (maybe 3" x 4" x 2") that has a finned heat sink on one side. I could make one, but would like to know if anyone has seen something like this in off-the-shelf (non custom).
I have seen finned U-shaped aluminum extrusions which incorporate slides for a PCB. To make it into a box, you just have to attach end plates, and a cover for one side. Power semiconductors are mounted to a flat area on the finned side.
I've used a metal box as a heat sink before and it worked quite well.
It was for an LM317 power supply. I soldered the tab to a piece of copper bus bar and mounted it to the aluminium case using insulating washers and screws. I used a thin piece of insulation tape to insulate the bus bar from the case.