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

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.