I liked andy_burke's idea for a coin holder, but when I printed a test print some coins fit and some didn't. So I thought it would be easier to just redesign my own one from scratch in Fusion 360. I decided to add a lid so that you could store banknotes or anything else in the centre.

.stp and .stl files included

Update: Added denominations and tightened up the tolerances on the lid as well.