Inside the Medusa

There's surprisingly little to this thing apart from the two chips (optoisolators for driving the Nikon remote) and the sensor (not shown - will install last, where the loop of black wire is on the front of the board).

The black patches on the sides are 3D printed templates for the battery holders. I printed out a flat keystone-shaped pattern, epoxied it to a circuit board (filling the holes underneath to make it easier to drill the holes for the batter holders later), and then trimmed off the sprues on the front and back. Piece of cake.

The faceplate and circuit board are currently held together with a 3D-printed shop aid, so that the wire lengths come out right when it's all transferred to the case.