Penrose Triangle Illusion

!! New version penrose5.stl with a couple of wayward vertices fixed !!

This is a 3D-printable version of the Penrose Triangle illusion, based solely on the 1934 design painted by Swedish artist Oscar Reutersvärd. The design also appeared on Swedish postage stamps in the early 1980s.

I created this 3D design entirely from scratch using the process outlined in the "Instructions" section below. This work is based solely on Oscar Reutersvärd's design, although some elements are inspired by the Hollow-Face illusion discovered many decades (if not centuries) ago.

This model contains a number of notable improvements over previous 3D representations:

1) It is parallax-corrected for a viewing distance of 40cm, i.e. it will look exactly like Oscar Reutersvärd's design, with cubes lining up on all 3 sides simultaneously. This is a great visual improvement over previous versions, which only lined up on 2 sides simultaneously.

2) It has been resized (to 99.43 x 99.65mm) to make ma