“Branching Support Structures for 3D Printing” by Schmidt and Umetani

Most 3D printing processes can be modeled by an incremental stacking of thin, flexible layers. In this case, it is apparent that for complex shapes, some stacks will be ”floating” in mid-air unless they are supported from below by additional material. Similarly if a slice is much larger than the one below it, it will droop unless supported. These areas are called overhangs [Evans 2012], and most 3D printing software provides automated generation of some kind of support structure. However, the support is waste, of both time and material, and this waste should be minimized.