Fit all the pieces into the box and close the lid.
Push-pull is a cubic box with double panels on the top side. Each panel has a 1×3 wing which sweeps into the 3x3x3 volume of the cube when the panel is opened. Five polycubes must be packed in the box with both panels closed. No trivial task, imagination and perseverance are definitely required. Design © Theo Geerinck & Symen HovingaMade in PLA