Inspired by [https://makerworld.com/en/models/589181](https://makerworld.com/en/models/589181) I like to believe my version has a little more style and function to it.

The holding ring has a hole for an M3 threaded insert but this hole is blind, ending in a flexure which should protect the microscope from the M3 bolt which needs to be inserted through the knob.

I set the insert by folding a thin strip of paper in half lengthways and inserting it into the slot at the bottom of the hole. This prevents the insert from melting its way through the thin wall of the flexure.

I printed in PETG for the additional robustness but it might work in PLA.