Caster Wheel Lock/Stopper

In my apartment, the floors are not level - to varying degrees - in several places. The slope is particularly bad where have my workbench. If your arms aren't anchoring you down to the table surface, you will slowly but surely start to roll sideways.

And this was my solution. v1.0 has a few quirks that I'd fix on another revision. I've stubbed my toe more than once on the sharper edges and the fit, while nice and snug, isn't always snug enough if I lift the chair to reposition it, causing a few of them to sometimes fall off.