When in doubt, 3D print the solution.
Following up on the mild controversy that the mucho expensive Mac Pro’s wheels don’t arrive with locks, a user has uploaded plans for the “Apple wheel chock,” or Apple wheel lock, on Thingiverse.
This is pretty nifty, and allows you to hash out an easy means of stopping the Mac Pro from rolling should the situation require it.
Take a gander.
Via The Mac Observer and Thingiverse