Designed to fit a 75mm bowl tripod for larger cameras. The purpose of this is not as a substitute for a real 75mm ball made from metal, but as a cheap way of holding up camera sliders or other items, and as a building block for other 75mm ball accessories.

If it wasn't clear enough, do not use this to support heavy camera equipment, it is a structural block meant to hold lightweight sliders.

Instructions

Requires:

• 3x 1/4-20" nuts
• 1x 1/4-20" threaded coupler nut
• 1x 1/4" washer (optional)
• 110mm long 1/4-20" threaded rod

Print all parts at ~100% infill for maximum strength. Print ball mount upside-down with support material.

Assembly:

1. Take two 1/4-20" nuts, thread them down onto the threaded rod so that they are ~3/8" from one end of the threaded rod. Jam the two nuts together with wrenches so that the flats line up. Press-fit the assembly (may require vise and persuasion) into the 75mm ball.
2. Secure the threaded rod onto the 75mm ball with the remaining nut.
3. Press fit the threaded coupler into the bottom handle.
4. Final 'assembly' - drop the 75mm ball down onto a 75mm bowl tripod, slide the bottom cap onto the threaded rod and tighten handle.

Optional: hot glue washer (friction reducer) onto either the cap or the bottom handle.

For future versions:

• Create a 3/8" version (or a version agnostic to thread size)
• Create some kind of retention mechanism to hold the bottom handle and bottom cap together for quicker assembly.