via Haptik's Cube by Threeheadedmonkey on flickr.

Rubik's Cube with black custom milled PVC-plates. Can easily be solved in total darkness :) There are mainly 3 symbols used: Square, Frame and Cross, which reappear also rotated by 45° on the opposite side of the cube. This allows the user to keep just 3 patterns in mind with 1 parameter each, but the patterns are clearly distinguishable.