Gerard Westendorpさんのイラストまとめ

Work in progress:
I am trying to picture a generalization of the modular group, in which integers are replaced by Gaussian integers. (a + ib). At the vertices on the sphere you get all Gaussian rationals (a+ib)/(c+id).
I hope to be back with more soon.

@Yugemaku , This would be a nice variation to make animations of. You could also do polyhedrons.