we took some big like 8 inch pvc from a construction site that we were painting houses at, and made some sweet rails or a tube if you will. Had like a 12 foot flat and a 7 foot one too. After a couple hours i ended up nutting it and breaking the frame...
Check out my thread in ski gabber. You predrill holes in the bottom of the pvc at the end, and screw the pvc pipes into the wood, then use liquid nails along the length of the pipes.