This mold is 3D-printed in ABS. It is used for casting bonsai pots, either in concrete or ceramic. You pour the material into the bottom part, close it with the top part, and tighten everything together with bolts. extra material will get out from hole on upside.

Before pouring the concrete, coat the mold with a thin layer of oil (vegetable oil works as well). After filling it, tighten the bolts and gently shake the mold to release air bubbles and ensure the concrete covers the entire surface evenly.