MakerFarm i3v MeanWell type power supply cover

This provides a cover for the terminal block area of a MeanWell-type
power supply when it is mounted directly to the MakerFarm i3v frame. The cover requires two holes to be drilled in the i3v frame for use as mounting holes. Although the openSCAD design can be tailored for other applications, the provided STL design assumes the power supply has been relocated to a custom set of M4 mounting holes raised about 28mm from the standard location. The Printbus i3v build repositioned the power suppl