A computer implemented method and apparatus for automatically adding utility holes to printable 3D models by accessing a digital representation of a 3D model; accessing specifications that define the geometry of a utility hole to be included with the 3D model; performing a heuristic evaluation of the digital representation of the 3D model to determine one of one or more possible placements of the utility hole to be included with the 3D model as a placement for the utility hole; modifying the digital representation of the 3D model so as to include the utility hole at the placement; and providing a modified digital representation of the 3D model for printing.