This took me 4 days to perfect, ugh.

Fits casters with mounting base 42.5 x 52 x 2.5 mm (four mounting holes)… these are pretty universal at least in North America. Prints without supports or brim.

The other end slips over a square leg that is 39 x 39 mm. Of course you can edit the model to fit whatever leg or post you want… the important side is the mechanism that latches onto the caster, which is what took 4 days to design perfectly.

2024-07-24-13-21 update: completely reworked the design due to unsatisfactory performance. Is the new design better? Only time will tell.