I made this to help someone iron out a specific infill problem on a part that had scallops and motor mount holes at the end of diametric's mini quadcopter arms, without having to print out the entire minicopter frame.

This part is 20mm in X & Y outer dimensions, 4mm thick, with 5mm and 3mm holes, and 7mm radius scallops. This was only an approximation of the actual arm ends.

Diametric's mini quadcopter:
http://www.thingiverse.com/thing:63822

An arm segment from the actual part:
http://www.thingiverse.com/thing:111024