rack hangers

These parts are for hanging things in 19" computer racks (and other places). The rack hanger was specifically designed to fit in 3/8" square holes in various places on the rack. These can be printed in either a hard plastic like PLA or TPU. These parts are meant to be used with a loop of string in a [cow hitch knot](https://en.wikipedia.org/wiki/Cow_hitch). The string hookend is designed to have a loop of string hitched over it, and then wrap the loop around a bundle of wire, and pass th