Full view is really needed to see what you have done here. My only critique is the "F" holes on the violin top and the shakiness of the purfling. I would think the F holes should not be so near the edge of the top. The purfling (edge or border ornamentation) would be smoother in it's flow. The tuning keys masking is a little rough too. The trick to making convincing images is: details, details, details
I'd probably paint/clone stamp over the f-holes, so it looks like a solid body guitar/fiddle. That and match the head shadowing to the neck a little better. I like the way you back lit it
Full view is definitely needed to see all the work done in uncompressed state. Overall an impressive work, but I agree with some points on improvement made above.