I recently made this helmet cam out of parts I had lying around the house. I used packing foam, hot glue, duct tape, velcro, and a piece of plexiglass (acrylic). I used an X-Acto knife to cut the foam, hot glued it together, and then used duct tape to create a better seal. The plexiglass goes against the camera lens. It’s big and ugly but it works, and it’s free. This was a concept that was made without any plans, so a lot of improvements can be made. But it still works well.
I can mount it to my helmet, handlebars, or almost anywhere you can use two straps to hold it. Since this was a prototype, I made it for my phone instead of my real camera, to test the sturdiness. The phone is an Ericsson P1i, and the quality of the video is better than most $50 helmet cams. Below are pictures of the prototype case and a video of it attached to an RC car. This case offers protection similar to the $30 cases found online or in stores, and with those you most likely won’t find one that you can mount anywhere and have it be compatible with your camera.
The next version will look much nicer, be more compact, more waterproof, and better overall.