This is a foldable 4-in-a-row chess with 9 x 9 grids. You may play it even for 5-in-a-row games. Each chess piece consists 2 halves. Just print and glue them together. For a complete set, you may need 42 black ones and 42 white ones (with 3 of them as spare). Also, glue the two cover plates together. Add 8 magnets (2 mm in diameter and length) for better holding the cover plate after folding.
0.4 mm nozzle with 0.2 mm layer height