[Tatu Salmela]

Are you sure the chamber surface is curved, not the reed channel cuts? With small-diameter router bits there can be some “stretchiness” to pattern edges, especially when removing too much material per pass. Usually milled surfaces tend to be flat and clean. Some of the waviness in the reed channels can be explained by hand finishing, the mill bit can’t cut sharp corners in a hole. On my cnc-milled reedplates, I had to hand-finish the reedholes by squaring the corners with a file.

Always when outsourcing a process, make very clear what is important in your design. If exact tolerances on the shape of the reed channels is not as important as the flatness of the surface, the round cornered rough channels in the lowest photo would do. If the shop has to do additional hand finishing, it shows in the price.

If I were you, I’d perhaps just ask if the surface was straight. Then I’d just pay for it, and test it once it arrives.