Currently I can print in ABS and PLA. ABS is what Legos are made out of. PLA is a more environmental friendly plastic.
In general the parts can be very strong if designed and printed properly. But because it's built layer by layer like a very precise hot glue gun, it sometimes can be fragile on some of the layers.
I think in the next 2 years we'll see another surge of new 3D printer technology hitting the homes.
My wife thinks I'm nuts, but I think in 10-15 years many households may have something like this.
There is something that is common place in many homes today that also started out as a kit built by hobbyists. The personal computer. I think this has a 75% chance to become something as common as a computer in the next decade or two. I could go on and on about why, and the impact it may have on manufacturing and retailing, but that might take a while.
And let me be blunt. Home 3D printing technology isn't mature enough at the moment. It's still more a maker/hacker type tool used for prototyping or making silly little plastic items. But as it evolves where it requires less tinkering and is as easy to use as our inkjet or laser printers of today it will start making more headway into less geeky homes.