A ring can be made of thirteen square anti-prisms. It is however, not quite regular. It can be shown that to complete the toroid takes approximately 13.01 square anti-prisms. It's a nice near miss though, and a physical model shows no visible distortion (stress map - cones exaggerated x 100). Distortion (E=0.041, P=0 , A=5.5°). It's not the closest such near miss; eighty-three icosikaitetragonal (24-gonal) antiprisms can be formed into a ring with an error of only 1/7700th of an anti-prism.