How do you go about getting something printed on mass that somebody else has designed and has posted the file for download.
Specifically the Who Dunnit reel fix,great idea but useless if you dont have a 3D printer,every WD will need these
https://pinside.com/pinball/forum/topic/who-dunnit-reel-fix
http://www.thingiverse.com/thing:691872

Shapeways can do it for a fee but the postage kills it if you just getting one part, so you could download from thingi upload the file as your own to shapeways (but I would chose the hide option as it isn't your design) and then print but most thingiverse models have a share but not sell licence to them. Or depending what it is I can can possibly print for a small fee.

Shapeways prints in various materials with the plastic being a rigid nylon material.

I can print in a PLA which is quite strong, but not ideal as a clear plan view part but if hidden will be perfect.

I just downloaded and I can print at 100% fill and post for $7.50. You are paying for the print time, plastic and postage.