The full number is therefore: [4] 3 4 × 4 ! 2 × 3 = 324 {\displaystyle {\frac {3 The purpose of the puzzle is to scramble the colours, and then restore them to their original configuration of one colour per face. The Pyraminx Duo (originally known as Rob's Pyraminx) [1] is a tetrahedral twisty puzzle in the style of the Rubik's Cube. It was suggested by Rob Stegmann, [1] invented by Oskar van Deventer, [1] [2] and has now been mass-produced by Meffert's. [1] [3] Overview [ edit ] The Pyraminx Duo in the middle of a twist, showing how the puzzle can be scrambled. The face centre pieces have no obvious orientation, therefore this does not affect the total number of combinations. The Pyraminx Duo is a puzzle in the shape of a tetrahedron, divided into 4 corner pieces and 4 face centre pieces. Each corner piece has three colours, while the centre pieces each have a single colour. Each face of the puzzle contains one face centre piece and three corner pieces.

The puzzle can be thought of as twisting around its corner pieces - each twist rotates one corner piece and permutates the three face centre pieces around it. An interesting feature is that the face centre pieces go "underneath" corner pieces during a twist. There are 4 corner pieces. Each corner can be twisted in 3 different orientations, independently of the other corners. Therefore, the corners can be orientated in 3 4 different ways. They cannot be permutated, therefore there is only one possible corner permutation. Mechanically, the puzzle is similar to the Skewb, with all corner pieces of the Skewb visible (although shaped differently) and all centre pieces hidden.