This minimalist birdhouse design is inspired by the strength and simplicity of the equilateral triangular pyramid. Since extrusion-based printing has inherent limitations, the pyramid was used for its printability without support material.

http://www.drsfostersmith.com/pic/article.cfm?aid=2194
using this page as a guide, I added these features to properly accomodate birds: a non-perch entry with an overhang, a covered vent for heat, and a drainage hole at the bottom.