Lou I use primarily ABS plastic, though I can print in PLA and some of the other experimental materials as well (wood, flexible, etc..) I model in OpenSCAD, which is math/programmatically based modeling, so very good for structural and functional parts but not so much for artistic pieces. I'm getting better and better at understanding what will and wont print right, and how I need to make my models to match the capabilities of my Makerbot Replicator clone. As far as a need, it really was more of a want/need to create. I've been following 3D printing and rapid prototyping for quite a while,