An insert 2 for use in a rotational moulding process, comprising mounting points for engaging the insert 2 within a moulding tool, wherein the insert is capable of contracting to accommodate shrinkage of a moulded article formed in the rotational moulding process. The insert 2 may comprise at least one bent section 4 and may comprise at least one U or V shaped bend. The bent section may be attached to the insert 2 along at least one line of weakness, which may comprise a line of perforations. The bent section 4 may be located at or near the end of the insert, and may be connected to a mounting point, which may project from end portions of the insert. The insert may have an arcuate section, and may comprise features to allow the flow of plastics material through the insert in the region of the mounting holes. These features may comprise slots or holes, and may be located around the mounting holes, and may additionally comprise barbs or hooks. The insert may be a light reflector, a diffuser, a solar panel, a st
