The OpenSCAD model is parametric, with a parameter for the number of glasses.  I found something similar (http://www.thingiverse.com/thing:878657/), but it was too large for my printer, and was only an STL, so I decided to make a parametric one, and it was influenced by that design.  Note that the design has holes for 3 screws, but because I didn't have many screws lying around, I only used 2 (one into the wall stud).