I like the metal shelves that come with wall control kits like this one, because they hold a lot more weight than you'd normally get with other options.

However, these shelving units have an annoying design flaw: Unlike most wall control stuff, the shelf itself tends to “jump out” of the vertical support arm tabs holding the shelf in position when there's no weight on them. This means that whenever you clear out a shelf you're risking having the top of the shelf slip out of the arms holding them up. Obviously this is annoying and needs to be fixed!

To fix this problem, I designed these little brackets, designed to be compatible with ~30 mm wide x ~1.75 mm thick double-sided adhesive (like this stuff). Once printed, simply apply the adhesive tape, and attach them to the shelves underside (2x per shelf, I find near the front as pictured helps the problem most). Problem solved!

I was reluctant to trust these shelves until I solved this problem.. but now that they don't spontaneously jump out of their tabs, they're pretty great.

Hope this helps someone else solve this annoying problem. STEP file included, because only meshes sucks when you want to make remixes :) .