Keyhole Hook for Metal Shelving Units with 1/2"x1/4" keyholes

UPDATE: Added keyholehookv2.stl, which fits much better and is slightly redesigned to accommodate even more weight at any infill. Please download this model instead of the deprecated keyholehook.stl (leaving for now, but will later delete due to inferiority versus the new version).

I whipped up a very simple hook design to fit in various metal shelving units that have 1/2" x 1/4" keyholes on support bars. These things realize a lot of storage potential for otherwise unutilized space on yo