The PC Tower we use has an exposed Power button at the bottom of the case (right at foot level). As a result, the machine ends up getting accidentally rebooted a couple times a week.

This part makes a raised rim around the button so that it can't be accidentally kicked, but it is still easily pressed when needed.

Sized for a reset button about 0.8 inches or about 20 mm in diameter. STL files are there for a 3mm and 6 mm thick version (6mm shown in photo). The Sketchup file is also included in case you need to resize it for your own needs.