This is a strap mount for a Go-Pro style camera. I needed something to mount a Garmin Virb GPS camera to the side of my bike helmet. I don't remember exactly where I got the various adapters from the pictures (may have been with a Swann Go-Pro rip-off I bought several years ago), but the threads on my parts are #10-32. Sacrifice the acorn nut from an adapter you don't need, an VERY CAREFULLY press it into the hex-shaped hole on the side. I printed it with 100% infill using ABS, and the fingers are still pretty fragile. But once everything is assembled it's not coming apart.
Solidworks file included for easy remixing.