If this is to be painted, what would stop you from using simple router bits and replicate the shape on thinner stock, then face-glue the whole thing together? Seems a bit easier to break the shape down to simpler curves than trying to replicate the whole thing. The biggest pain is to have enough clamps to secure the whole thing together, but that does give you a reason to buy a bunch of nice new clamps (and considering they're useful in metalworking as well, that's not so bad!).