The PCB Rax is an easy to use, versatile printed circuit board holder for repair, prototyping , and assembly that can hold nearly any shape of circuit board. Check the details on the link below.
Not all circuit boards are rectangular. PCB Rax was designed to hold all kinds of different shaped circuit boards, from circles to christmas trees, and everything in-between. PCB Rax comes standard with 10″ connecting rods that can hold rectangular boards up to 9-1/4″ x 8″, and odd shaped boards up to 6-1/2″ x 8″. For larger projects the connecting rods can be replaced.
PCB Rax – A modular system for holding circuit boards – [Link]