One could envision something like "Take a photo of your broken thing", sending that photo off to an industrial/mechanical engineer who lives in (without loss of generality) China and can be employed profitably to do non-trivial work in CAD software to save $X0, and then sending the resulting IP to a local 3D printing firm who'd maintain expensive, fiddly equipment, make sure the printing process terminated successfully, and then give the product to either a gopher or UPS for delivery.

Now I question whether that makes more sense along any axis than "Buy a new alarm clock from a more-or-less-locally cached store of Chinese alarm clocks and cut out the middlemen", but it might be interesting to try.

What makes more sense (and that I've done myself) is to print out a part for some expensive appliance where the parts are either extremely expensive or just not available at all. For instance, a $1000 automatic espresso maker can have lots of moving plastic parts, and the rest of the machine might be in perfect working order save for that one broken part. And when you've made the replacement part it's easy to print another one, and share it with others.

Or another example (from some years ago), just to get one replacement part for my perfectly fine shower cabinet, I had to buy a complete set of plastic mounts, to the price of $160.

One could create a line of "open-source appliances", that had ease of maintenance as its main selling point, although catering to a part of the market that prefers fixing rather than buying stuff can be a little tough.

They probably don't need to be open-source appliances, though firms that insist on suing people who post open CAD drawings of their machine's parts will incur a competitive disadvantage.

What will happen is that groups of hobbyists will rapidly converge on the machines on the market that fit in a sweet spot of good design, affordability, and mod-ability, then amplify the effect by building up open libraries of printable parts.

I think of all the Honda Civics I saw in California. The Civic is a long-standing hobbyist car. Or think of all the iPhone add-ons you can buy or make. The iPhone is a far cry from "open hardware", but it's still a standard base for a hobbyist market.

I do wonder whether this is the sort of thing that will push 3D printing across the chasm, but that doesn't mean it's ridiculous. One must start the market somewhere, and there seem to be enough hobbyists and prototypers around to keep things moving forward.

or scan the box to pull up a parts database, click on the part you need replaced and have the printer pop it out.