It was tricky to get the curves right on all the pieces, but the backplate is the one I couldn't get to work at all. It was fun making the parts myself, but I think it would have been cheaper in the long run to buy from RKD. It takes a while to get everything cut out (templates, sintra), then glue the extra bits along the edges to make it appear thicker, sand the edges smooth, heat the material to get all the curves, then heat it again to put in the dents. I probably spent 4 or 5 days messing with the backplate alone. At $75 from RKD, it was a no-brainer to scrap it and buy from him.
Good luck with your project
Queso