Pyramid screw-puzzle by George Hart

thingiverse

I've rounded out two of the inside corners, so that the wall thickness no longer approaches zero. In the comments of the original, people had noticed, that the object would "break". Done with FreeCAD. Convert mesh to part, then use the part as base-object in part design. Sketch the round corner shape onto one of the inner surfaces, then extrude along the edge where the thickness becomes zero. There are two instances, where this is needed. The inner surfaces are still as rough as with the original. Could not find a simple post-processing to fix that. I've also expanded the size by to 133%, in the hope, that this helps with the tight tolerances.