I'm just thinking about getting a 3D printer but have heard some say that you have to buy proprietary filaments for the 3D printers currently out there. Is this true? Will I be stuck paying for expensive filament material if I get a 3D printer? Are there any 3D printers out there that use common sizing on their filaments? Are there any generic filaments out there that are still good quality that can be used on different models of 3D printers?