I have not been too impressed with the sudoku cubes that are currently on the market. For starters they can’t follow all of the sudoku rules. Sure, each face of the cube contains the numbers 1 through 9 but that’s it, the rules don’t go beyond one face at a time. If you follow a column or row all the way around the puzzle you find that there are 12 places for numbers, so the rules of placing numbers 1 through 9 with no duplicates just can’t be applied to a 3x3x3 cube. Also, I feel that the fact that printed numbers have an orientation to them gives away too much when solving one of these cubes. If you places to pieces next to each other and the printed orientation of the numbers does not match, then you know that these pieces are not positioned correctly.
In order to apply the sudoku rules across all surfaces of the puzzle I used a 4x4x4 cube and 16 numbers instead of 9. This allowed me to have all 16 numbers on each of the 6 faces, without duplicates. Also when you follow any column or row all the way around the puzzle, you will also find all 16 numbers.
The next thing I did was get rid of the numbers. In order to fix the printed number orientation issue I assigned a different color to each number. The16 different colored stickers have no orientation to help you with solving the puzzle.
When working out the pattern I first used numbers as it was much easier to arrange and rearrange them as necessary. I also took care not to have any duplicated edge or corner pieces. I then assigned the following colors to the numbers:
2 bright orange
6 light gray
8 light purple
9 bright green
14 light blue
15 bright yellow
Any colors could be used so long as you use 16 different ones. I chose the colors above based purely on what I had available.
There may be more than one solution to this cube. I haven’t studied it enough to determine if that is the case or not. Also, I have not scrambled it yet, I’m kind of afraid to