Believe it or not my latest addition to my spearguns is not one for shooting fish (well at least not shooting to kill them). But it hopefully will help others watch online what I love to do underwater. I have made a camera mount for my Riffe Euro guns. This mount will fit on any Euro that has the reel inserts (basically all of them). It was terribly simple to make. The only fairly tricky part was putting together the actual mount screw for the camera tripod mount itself.
The piece is nothing more than a single piece of stainless steel (I used stainless, it could have been aluminum) with 3 holes in it. 2 - 7/32" diameter holes 3" apart (to fit over the reel inserts) and one more 1/4" hole out at the end to accommodate the tripod mount screw. The piece can be left on the gun or put on and taken off as needed since it's no harder than removing and replacing the reel itself.
The tripod mount screw is actually put together from a 1/4"-20x1" allen head screw, a 1/4"-20 wing nut, a nylon fender washer and last but not least a 7/32" rubber fender washer. The nylon fender washer is primarily to give the camera case some traction on the metal when you tighten the screw down. The rubber fender washer's function is to hold the screw in place even when the case is not mounted (hence why its hole is smaller than 1/4").
Once the screw has been aligned with the bottom of the case, you simply finger tighten the screw. Once the screw bottoms out on the tripod mount, you then tighten the wing nut and that clamps the case down against the niylon and rubber fender washers holding the camera firmly in place. From that point on, any time you want a picture or a video, simply put the camera in the correct mode, and press the shutter release... Voila! you're an underwater spearfishing videographer. Not too shabby if I do say so myself (so I will).