the object of the puzzle is to get the square block through a slot in the bottom of the frame. for printing, you need four of the 1x1 blocks, and five of the 1x2 blocks, and the 2x2 block. 

There's two versions of the frame- the solid frame will need to print with supports. 

For a smoother surface for the puzzle blocks to slide on, I separated the base and the walls, and glued the two parts with the bed-side up. I printed the base with modifiers, with hexagonal infill  at 20% and zero top layers (this becomes the bottom in the final assembly) otherwise infill in the blocks and frame are whatever you prefer.

The blocks should be a close fit, but slide easily. if they don't, you may need to scale the individual blocks.