This is the joint! This is the jam...For building structural truss systems both simple and complex. It is made from two repeated sheet metal parts and off the shelf hardware. It has eight ball joints that make an octahedron for finding compound angles for curved/doubled curved surfaces with a rigid frame. This joint does all of the hard work so assembly is fast and easy!!
In short: design a truss system. make the joints. cut your rods. screw it all together by hand