A mould for forming a collapsible container from an expandable material, the container comprising, at least a base and two pairs of a side walls extending at right angles from opposing sides of the base, the mould comprising: a first mould member and a second mould member movable with respect to each other between an open and a closed moulding position to define a mould cavity; and a plurality of anvils mounted on a rear surface of at least one of the first mould member and/or second mould member, each anvil being movable so as to be extended into the mould cavity so as to form one or more hinges in the expandable material at predetermined locations within the mould cavity; wherein the mould cavity defined by the first mould member and the second mould member is a three-dimensional representation of an inside-out configuration of the assembled container.

One aspect is an insert molded torsion bar hinge including a cylindrical metal torsion bar with a main bar body, a portion of which extends along a torsion bar axis, a first contoured bar end and a second contoured bar end on opposite ends of the main bar body. A first hinged element of molded plastic and with a first knuckle, is molded directly over and encompasses the first contoured bar end such that the first contoured bar end is fixed within and not rotatable relative to the first hinged element. The first knuckle is molded directly over and encompassing a portion of the main bar body. A second hinged element of molded plastic and with a second knuckle is molded directly over and encompasses the second contoured bar end such that the second contoured bar end is fixed within and not rotatable relative to the second hinged element. The second knuckle is molded directly over and encompassing a portion of the main bar body. The first and second hinged elements rotate and produce a torsional spring torque.