A rotomolding machine is a type of plastic molding machine that uses rotational molding to produce hollow plastic parts. Rotational molding is a process where molten plastic is poured into a mold and then rotated to evenly distribute the plastic around the mold. The part is then cooled and removed from the mold.

Rotomolding machines typically have two or more arms that hold the mold in place while it is being rotated. The arms are mounted on a central shaft that runs through the middle of the machine. The molten plastic is injected into the mold through a port in the arm. The arm then rotates the mold, ensuring that the plastic evenly coats the inside of the mold.