The prototype boards arrived, and they look awesome! The PCB material is of a dark violet color, and all the solder pads are golden. I ordered them at OSH Park, where you'll always get (multiples of) 3 boards.
|DX7 cartridge prototype boards, rightmost already populated.|
Now, instead of throwing them away and order another batch with the proper dimensions, I'll use them as tinkering material. I already ordered a small sheet of blank double sided circuit board, which I'll cut to size using a high-tech template that I made from an obsolete phone card.
But first I have to wait for the blank PCB to arrive.