I made up this puzzle a few days ago and I couldn't resist sharing it.
You have a set of oddly-colored tetronimoes. The idea is to put them in the target shape in such a way that the colors on the pieces also form different tetronimoes. This is a little difficult to explain, so I made a simple 4x4 puzzle and added the solution so you can see what I'm talking about. See If you can solve the three others! I'll add more as I make them.
Tetronimoes^2 4x4 Example.png
Tetronimoes^2 5x5 Void.png