This is my first time uploading a model, please excuse any mistakes!! I saw a version of this on Thingiverse and thought I'd make my own with fewer holes. I'll add a link to the original when I find it! 

I work at a library and wanted a way to display the colors that we carry, so I modelled this to match the number of filament colors/types that we have on-hand. I printed out the XYZ 20mm calibration cubes to fit inside. 

It's not a very complex model, so feel free to adjust as you need it! I modelled this on TinkerCAD so that I can show patrons a fairly easy way to start modelling prints. 

Doesn't require supports. Printed mine on a Flashforge Adventurer 5M Pro with black PLA and it worked just fine! The fit was a bit snug for the cubes, but I was able to force it in with little problem. I'd maybe scale it up a bit if you're going to be switching out cubes regularly.