A flap (21) is inserted in a similarly shaped and sized tubular opening (22) with the aid of a tool (10). Slots (23) are engaged by hooks (14) on the tool and the tool is inserted into the opening (22), thus entraining the flap (21) therewith. Upon withdrawal of the tool, the hooks automatically disengage from the slots so that the flap (21) remains within the opening (22). As described, the flap (21) and tubular opening (22) constitute opposite ends of part of a disposable paper hat.