Triangular Key for some european cabinets, most elevators here in Spain, and some electrical boxes. It can open elevator doors in case of emergency, useful and nice looking for daily carrying. Use supports and 100%infill. I modified the robust body from https://www.thingiverse.com/thing:1764169 improving the keyhole to fit these locks.

v2: I improved a bit the keyhole and made thinner the outer diameter to fit some thinner holes.