Disc D72 is perfect for building symmetrical mechanical structure such as 120 degree three-wheeled car, three axis helicopter, four axis helicopter. Besides, With a 72mm diameter, you can also  use it as base plate.
 
Features:
8mm diameter center hole compatible with 8mm shafts or bearings and can be attached with DC Motor-25 and Stepper motor due to M3 mounting holes
with M4 mounting holes and 4mm mounting slots compatible with Makeblock components.
Made from aluminum extrusion (high strength), 3mm thick, anodized surface(long time to shelve without barely rusting)