Super clever stuff coming out of Disney Research, in which they define balance points of 3D printed objects via internal channels and sliding mass.
The latest project from Disney Research, which is often busy with impressive projects involving 3D technologies, involves the creation of 3D printed objects capable of performing gravity-defying feats of balance.
Source: Disney Research Devises a Method of 3D Printing Models That Balance or Breakdance | 3DPrint.com