You should be able to get it printed, I designed a mould for my custom intake manifold using a 3D printer. As I only needed the ends mating nicely I used a scanner with rule (for scale) to get the correct alignment. Then worked some carbon wizardy with the mould.
if you’re on Facebook 3dprintmyride is full of people that do just what you’re after some have access to CMM’s, although I’ve not used mine for car parts they will give a very accurate measurement of your other side which can be flipped on cad easily enough prior to printing.