starting from reprap a few years ago, 3D printing has been evolving at full speed. Most that we've been talking is based on fused filament, by using filaments of ABS or PLA. From one research, the market is mainly dominated by MakerBot, RepRap, Objet and other long time industrial makers, eg Stratasys, zCorp and some others. make magazine , wired , tested has been talking a lot Bre Pettis of MakerBot also talked on TED 2012 MakerBot TV on youtube: What is 3D printing from www.3dprinter.net Every thing you want to know about 3d additive printing