Cubical Hook for Steelcase office furniture. I modeled this after the original. I also designed it to be thicker for a tight fit and to make it more rigid. The original metal hook has a loose fit and wobbled a lot. I printed this in PLA on my MP Select Mini with magic number layer height of .0875 @ 100% infill so the finished product would look good and for strength. So print accordingly if you have a different printer so that it will fit.
I have also uploaded a narrower version of the hook in case you would like a looser fit.