Okay, I've only done one, so far. I'm not sure mods for Minecraft are a real feat, but it is written in Java and was a good learning experience.Cube's PuzzleCubes Mod
Minecraft Version 1.7.10, Requires Forge
This mod adds several Rubik's Cubes to the game. They are generated with the world, you must have the mod installed when you generate the world. It will place 2X2x2, 3X3x3, and 4X4X4 Rubik's cubes throughout the world.
Generally, the 2x2x2 cubes behave like dirt. They spawn higher, break easier, and will drop when broken by hand.
The 3x3x3 cubes follow stone. They spawn lower, are tougher to break, and must be mined with a tool to drop as an item.
The blocks based on the Rubik's Revenge puzzle are much deeper, harder to break, and also require mining with a tool if you want them to drop as an item.
All of the cubes are found scrambled, and drop an item block that's solved. You can scramble them back by crafting . . .
You can then solve them the same way . . .
You can craft all of the tools out of the cubes . . .
The cubes you craft with must be solved, though . . .
All of the additions are available from thier own creative tab.
I'm not sure why I didn't include armor. Maybe in the 1.10 update!