Most of them think that 3D printing is like printing photos or printing a newspaper etc. But it is not so. It's a 3 dimensional part making process been made on a 3D printer to actual size or in required proportion, as a prototype or maybe as production if quantity is less than 200. The difference between conventional machining and 3D printing is that in conventional machining we remove material not required and make part as per drawing, where as in 3D printing its an additive process thereby layer by layer material is deposited on a printer plate and parts are made. Common material used for 3D printing are plastic and ABS (the material used for telephone etc.