Arched Classical Guitar Back - Fusion 360

I am a luthier. I build Classical guitars. I recently designed an veneering mould for an arched back classical guitar back in Fusion 360. I want it redesigned as it wasn't quite right. I have all the drawings done in fusion but I have not learnt to use the Sculpt environment that good yet need someone to finish the from. The Mould needs to be in a rectangular form and in reverse so I vacuum/glue timber veneers into it to build up the shape. I have attached images of the shape of the back I am looking for. 1 image is of the mould I already made and the mould in use.