Abstract: Disclosed is a collapsible plug which is insertable into the interior section of an appliance cabinet and expandable therein to simultaneously extend the plurality of panels to provide lateral shoring support to each of the interior surfaces of the cabinet so as to prevent bulging thereof during the injection and curing of insulating foam in the cavity between the interior surfaces and external surfaces of the cabinet, and collapsible so that the plug can be inserted into and removed from the cabinet interior without contacting the interior surfaces during insertion nor removal. Particularly, the disclosed design allows different thicknesses of tooling panels having surfaces complementary to the interior surface of the cabinet to be employed without concern for contact between adjacent panels upon their retraction due to the additional thickness.