When I was looking for waterproof cases I bought two: a waterproof flashlight and a cheap GoPro waterproof case (about $15). With the success of Design 2 (flashlight), it's time to try out Design 3.

The GoPro case is a rather splendid little transparent cube, with enough space inside to accommodate the camera and the video balun. The case unclips making the internals easy to access. There are a couple of waterproofed buttons which are used to trigger a GoPro camera ... if one were inside, and by removing one of these I was able to pass the 4-wire tether from outside to in. I had originally feared I would have to drill the case but this was better.

Unfortunately this hole was far too small to accommodate a waterproof gland (as I'd used in the flashlight design), but the cable still needed to be waterproofed. As much as I wanted to avoid it, I used Marine Epoxy to fill the space around the wire on the outside of the case, and so make a waterproof (but permanent) seal.

The design of the case made this sealing very simple - the hole allowing the wires into the case was small enough for 4 wires but no so big to allows the epoxy to drip in, and the outside of the case had a circular wall while held the epoxy on the outside making a good seal. It wasn't design for this, but it really couldn't have been better.

Once this is dry, it will go into the water for a first test.