Magic Blocks Deluxe by 7 Magic
The building block miracle is a true magic puzzle!
For the puzzle part: the performer starts by showing that the puzzle fits into a frame as a rectangle. The performer rearranges the blocks and the blocks still fit into the frame.
Now for the magic part: the performer adds a block from his pocket and yet the puzzle still fits the frame and as a climax - The performer adds a second piece and the blocks still fit!