Made a new hatch for my Starmax F-18 . Front and rear formers made from 3/16 ply . Two 3/32"X1/2" stringers to connect the two formers. Epoxied two 1/2" sheets of foam onto it(oversized). While I was waiting for the epoxy to dry on the foam I put together a foam cutter. I bought the parts for it for about $14 at lowes. Hooked up my battery charger leads and cut off the excess and voila! new hatch. I had to sand and fill some, then paint and all done.