I made the X rail supports and gantry for my Solsylva 24x48 this way. I just laminated birch plywood. Rather than go buy a ton of clamps, I vac-bagged them. I used slighty thinned Titebond 3 brushed on both sides of the bond. After they were glued together, I rounded them with a radius bit in the router and bonded and screwed on some steel angle for good measure. I had to put the radius because the inside corner of angle iron has a radius and it won't sit flat if you don't do it. I'd guess that the resulting beams have greater stiffness than extruded aluminum beams, and much better dampening.