This is an old sliding puzzle. A simple puzzle to make but fun to play. You start with,
PANAL empty square at bottom right
And you try to make,
CANAL by sliding puzzle pieces. The solution of this puzzle require minimum 21 moves. I cut puzzle pieces from 30 x 10 mm ready stock. Each puzzle piece is 30x30x10 mm. For making the try, I used 10×10 mm ready stock and 10 mm plywood. If you round corners a little and chamfer all edges, pieces will slide better. For sliding puzzles, ı advise making the try 2-3 mm bigger than total pieces dimensions. If you want play and test before making this one, you can play online here.