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I made my version with the V of the block oriented upward for the best finish, and organic supports. As I did not have access to the original files, I am offering the gcode that resulted from my tinkering in the slicer. It is a long print, but worth it if you are using it as a demonstrator for students, as we will. If you start with mathp's model and cut away that opening yourself, you will be able to change the other parameters to suit your needs best. 

We may end up lasering a little clear acrylic window for the opening, just to keep the dust out.