3D printing will give pretty much whatever finish you want, depending on the material that you print with and the definition of the printer or print program.
I commissioned a trip reset winder a couple of years ago, as I lost mine and found they are no longer made or stocked.
First step is to draw a 3D CAD file accurately from a bona fide original item (or pair in this case.) Next step is to find a (preferably local) printer with suitable equipment and able to produce economical one offs. Choice of material is critical in this case as the part needs to be strong but flexible.
I was lucky in that my brother is a very experienced 3D draughtsman. Slob also helped me with the printing process. In the end a local chap who had just acquired some very fancy kit, printed the part to perfection and we discovered the print regime that suited that part.
You can see, and manipulate the model with your mouse, here; post #57
http://www.ukmonster.co.uk/monster/s...+winder&page=4