These are a set of hinges for the enclosure designed by Mike Kelly. Here: http://www.thingiverse.com/thing:681843. These hinges can be installed without drilling any holes in the Robo3d cover. You would thread and install 2 set screws in the 2 holes shown. You slide the hinges onto the case and tighten the set screws. The part of the hinge that goes onto the plexiglass has 2 holes but I found that there was only enough room for 1 flat head screw. If you want to use 2 screws, you would have to make the hinge longer. Or you could use 2 socket heat cap screws.
These Things have been updated. The latest update date is 1/13/16. They were made thicker and changed so that the two screw holes on the latch were further apart to put 2 flat head screws in.
A drilling jig has been added to assist in drilling the holes in the acrylic. You just place the jig up against the plastic and drill 1 hole. Then put a screw through that hole to hold the jig in place. Then drill the second hole.