I have this signcutting machine, I found that by replacing the knife with a ballpoint pen i could get pretty good fullscale drawings.
Otherwise i use 4mm MDF board or where there is plywood bulkhead i ssssimply drew on to the plywood. The Fuse is pretty much sanded to shape. Only bulkheads where engines/landinggear and other strongpoints dictates a need. Otherwise just foam!
Jonas