Springy Hold-Down Bracket

Brackets to hold objects to a surface, like a shelf, desk, or project board, without any changes, such as the addition of screw holes, to the object itself. The stretched springs, when screwed into the surface, do not need to be exactly the right length, and the stretched spring provides a useful hold-down force.

You may also want to see a version that uses a compression pad (probably printed in TPU) rather than springy legs: https://www.thingiverse.com/thing:6938181