3D printing has been around since around 30 years now, but it was only for professionals and big design bureaus. In recent years this technology has trickled slowly into mainstream and is now accessible to the masses as the printers get cheaper.
The technology that most of the low budget FDM printers are based is surprisingly simple and old school. The communication language is G-code and was used in CNC machines and other automation system since the 50s.
So I got myself Solidoodle 2 3D printer last year. After ironing out most of the kinks that where mainly caused by the free open source software, I am now happily printing away whatever my brain spits out.
Most models are freely available on Thingiverse along thousands of other models from users allover the world, with a few gems peppered in here and there.
Some are also available to purchase either as a print at Shapeways or just the model to print yourself at Cults3D