Abstract: A swing head assembly with a swing head and pin affixed to a first horizontal member. A vertical member with a rosette positioned in coaxial alignment therewith. The rosette has radially arranged cut-outs for receiving the swing head assembly. The swing head assembly is rotatably coupled to the rosette. A second horizontal member has a horizontal member head at an end thereof. The rosette is also able to also receive mating elements of the horizontal member head, the second horizontal member having therein an internal wedge assembly with a wedge portion that extends and retracts from the horizontal member head to lock and unlock the horizontal member head to the rosette. The invention further includes a horizontal member having a swing head assembly at one end and an internal wedge assembly at the second end thereof.