3D printers are a bit odd. In their current form, I will whole heartedly say no one will use them (short of the tinkerers and creatives). It's not like email where I can go on and connect with someone. It doesn't give me something that I didn't have before. I can't print the expensive things in my life, I can print stupid things like cups, cases, boxes, clips, holders, etc. Light things, cheap things. I can customize them, that is the huge thing 3D printing allows - customization. Short of that, it doesn't have any of the fancy flashery that electronics do.
This isn't to say that it won't happen, but it needs a new spin. It needs the 'killer app' that makes people want it. 1 Kg of ABS plastic (1.75 mm in diameter) is ~$30. PLA is more expensive, but it is renewable (~$45 / kg). It's not free to make stuff once you have one (it will last for a while, but you'll still need raw material).
They are slow, at least for 1D printers (filament printers are parametric printers, we move our nozzle in a line that gets longer with time). SLA printers are faster, way faster. They print planes at a time. They also can have better resolution. The trouble with them is that the liquid material is significantly more expensive as they are UV cured (so they need special handling, and whatnot).
I've been trying to think of something cool for what could be done with the situation (as it would get me a lot of money), but it's a hard problem. We're spoiled by how luxurious electronics are, how precise they are, and how little we have to think about how well they work. Little electro-mechanical things would be cool, and I could probably hand out a lot of personalized presents, but do I really need one in my house? Yes. Do my parents need one in their house? No.
I can get a personally engraved iPod in a startlingly short period of time.
Lean manufacturing has been pushing towards the idea of pushing different things off the end of a production line for years. They'll carry on doing that. As the technology improves they'll integrate 3D printing type technologies into the supply chain.
Personalisation is certainly interesting - game changing in some instances almost certainly.
That doesn't mean that it's going to happen via 3D printers in your home. I find it hard to think about any kind of personalised object that I'm going to need urgently enough to print now gosh darn it, rather than wait for next day delivery. Especially at the ongoing cost of another box taking up space in my house.
I might have one coz I'm a sad techie who loves fiddling with stuff... but that's not a mass market. That's in the order of magnitude of the home-CNC machine/lathe market.
I can imagine technologies that might hit a mass market. For example if printing and disposing of kitchen mugs / saucepans / cutlery / etc. becomes cheaper/easier/smaller than buying / storing / washing them up then I'd buy a 3D printer like a shot. That kills a major pain point for me. But nothing like that is even vaguely close.
I've yet to see any problem that will persuade 'normal' people to get a 3D printer in the home that's anything close to an implementable reality. I'd love to get educated if I'm wrong ;-)
I'm thinking more ~20 year horizon than next five years. I don't know if 3d printers will advance at the rate that transistors and microchips have, but I expect in ~20 years they will be able to do some interesting things.
Sure, but once you're printing them at home, they're no longer cheap. The material that a manufacturer uses to print a million items will be purchased at wholesale prices. Your onesy-twosy items will be priced retail costing orders of magnitude more.
It doesn't matter if, in aggregate, 50M people buy more than a manufacturer does. Each of those people will still get worse pricing than the single large-volume manufacturer would.
The economies of scale in producing the raw material will likely mean that its price will drop a bit, but the guy buying 5 tons a month will always get a much better price than the guy buying 5 lbs a month. Even if there are 50 million guys doing the same thing.