This is exactly the sort of niche that fully automated single-part manufacturing equipment can fill.<p>While you&#x27;re not going to be able to print a replacement part for a mechanical watch with a RepRap any time soon, a specialty machine that could duplicate parts by putting the original on a microscope slide and taking some photos could be useful whenever the replacement parts are unavailable from the manufacturer at a lesser cost.<p>Some hobbyist-grade volume printers and CNC mills have been employed to make car repairs in instances where the manufacturer sells for $50 some nylon gear assembly that contains $0.10 of plastic and some commodity steel axle pins.  Sometimes, the nylon is replaced by CNC-machined aluminum (at higher materials cost--maybe $2 instead of $0.10), and that part will never need to be repaired again for the lifetime of the vehicle.<p>Such one-off manufacturing moves the market from zero competition, where the market can be manipulated and controlled, to a more competitive model.  Even if the original manufacturer can create a replacement part at 1% the cost of a home-repairer garage-manufacturing a part, the threat of it places an upper limit on what the business can charge for their officially sanctioned repairs.<p>It is the manufacturer&#x27;s refusal to sell those parts at a reasonable price that creates the market opportunity.  Every complete new watch must necessarily contain working parts.  So someone buys one, takes it apart, makes detailed photographs, and discovers the means to duplicate the parts.  It&#x27;s not whether the parts <i>can</i> be produced at lower cost, but whether they are made available for sale by anyone at lower cost.  If it costs you $20 to make a part that <i>can</i> be produced at $0.02, it hardly matters to you if the only way you can get that is by paying $100 and shipping to and from the factory.