This is a frame to mount multiple extruder motors to older style ultimakers that only have place for one. The electronics can handle two hot ends, and so can the flying head, but there was only room for one extruder motor. This frame solves that problem by allowing four (why stop at two?).
Cut this out of 6mm or 1/4" plywood with a lasercutter, cnc router or whatever you prefer to cut plywood with. Measure out where you wish to mount it and drill one of the holes. Level the frame and mark/drill the other holes. Add the spacer things between the mounting frame and UM backside and screw it together with M3 bolts nuts and washers. You may wish to add some glue when you are happy as I've had some reports of the holes being insufficient after longer use.
Licence note: There is no more licence rights to give apart from the CC-NC-SA. I thus do not and can not grant thingiverse any more rights than that. Fix those ToS, thingiverse!