Cabane struts made from 1/4" steel rod with 1/8" steel rod cross bracing brazed at their joints. Top wing is held in place by nylon 1/4x20 bolts screwed into a threaded insert at the top of each 1/4" cabane strut. Outer wing struts are 1/8" birch ply fastened upper & lower with 4-40 bolts thru strut into blind nuts fastened to 1/8" ply tab built into and protruding thru the top and bottom wing.