I created this remix from Mike's excellent model, after having printed the first set of parts. This was done to add additional nut & bolt holes to help keep the two parts hold together (I suspect they were a bit warped) and closing the holes to make it simpler.

This may use a bit more filament (but not much) but takes about the same time to print (if I remember correctly).

You can see in the photos that I kept Mike's, and that the two parts hold together quite well in fact. But it was a great introductory exercise into FreeCAD.

The filament guide shown in the pictures is here.