Ok one thing that can be a little tricky is getting the Gemini in a perfect orientation to set level. This is due to no flat surfaces, except for the small area under the motors on the CF "legs". I have just completed my design of the 3D printed Gemini leveling stand. It consists of a base with two circular posts which insert tightly into the holes underneath the center two motors in the CF frame. These posts press in until the frame rests against the larger diameter of the stand. When flush the printed base will provide an easier way to ensure the Gemini is in the proper orientation for setting level. In front of the base is an arm with protruding stand-off with a recess for a standard 1/4-20 nut and large head machine screw. This screw can be threaded up or down, pressing against the bottom case (towards the front of the Gemini) until the motor shafts are perfectly vertical. If the 3D printed base is placed on a perfectly level surface, and the machine screw adjusted until the motor shafts are vertical, you can be assured of a perfect hovering position in which to calibrate level. Important I scaled up this model in X and Y by a factor of 1.019 (No change in scale in Z however) to allow for ABS shrinkage on my printer. You may need to alter this scale somewhat for your chosen printer and material type to get it precisely correct dimensionally. Update 2-17-15: I have added a new version! Rev B includes a smaller outer base for faster printing, a groove on each side to provide a visual cue for vertical as an alignment aid for the motor shafts, and slightly smaller diameter inserts for engaging the base of the Gemini easier.I used 20% infill and 2 shells. No supports are required. Please note that the file has been scaled up in the x and y axes by a factor of 1.019 to allow for shrinkage on my printer when using ABS. Your printer may behave differently, especially if you use a different material than ABS.