This clamp is designed to mount Modular Mounting System components to a 16mm tube.
If you need other sizes, you can use the linked OnShape document as a starting point to create them.

The hinge pin is designed for M5 x 30mm steel pins which are easy to find on Amazon, or you can use an M5-0.80 x 40mm bolt and nylon locking nut.

The clamping hardware used is a 1.5in 1/4 x 20 bolt with nut and washer.

I've also included a compatible knob for convenience.

GoPro compatible

Configurable OnShape model: Tube Clamp - Fixed-Bolt

Check out my Configurable Bolt Knob to create knobs for this and other projects!