Wheel chock for office chair

I use an under-desk elliptical machine, and to keep from rolling myself away from my desk I need to prop my wheeled office chair up with these wheel chocks.

The STL “for rubber insert” is designed to accept the rubber grippy insert from the wheel chocks that come with the Cubii under-desk elliptical machine. The wheel chocks broke over time (probably would have been fine if I was on hardwood or tile floors but this is on a plastic mat on carpet, not as rigid) but the rubber inserts to give them grip were perfectly good, so I adapted my wheel chock to accept them.

Also added a more generic wheel chock design that I use under the wheels of a Harbor Freight furniture dolly that I have my generator mounted to so it doesn't go walking off when it's running.