Hi I am thinking of replacing the bed frame in my van, it appears to be 2x2 and 2x3 iron and weighs a ton. I would like to replace it with KJN’s 30x30 or 20x20 aluminium extrusion. It looks as though KJN offer the best range but I want to design the frame on a CAD/CAM software, free if possibl, which is the best to use that may have the 20x20 already programmed in?