I'm planning to do marquetry on the back of a banjo resonator and would like some advice. I've done marquetry on flat surfaces, but never on a curved surface. The back of a banjo resonator is slightly convex. It's just over 13" in diameter and has a radius of about 40" plus or minus. It's not a lot of arc, but it's more than just a little bit. I think maybe the "peak" of the dome is about 3/4" higher than the edge. I hope that makes sense. My question is: Should I layout the pattern on a flat surface, join all the pieces, then apply it to the surface, or--- should I build it on the curved surface? Seems like making it flat would allow me to get tight accurate joints, but I'm not 100% sure it would conform to the curve.
If I should build it on the curved surface, I'd be eager to hear any tips for doing this. Any guidance is greatly appreciated.

I'm far from an expert but I did build some marquetry/inlays for a kayak deck with a 16" radius. I built them flat and then used a jig with the same radius as my final surface and clamped it there for a few days before final assembly. I had a minor amount of springback (the inlay pieces were maybe1/4"-3/8" thick if I remember correctly) so consider that when you do it.