In the case of inkjet 3D printers, the composite powder used may be based on plaster or cellulose (the most common is the plaster). The result is quite fragile, so you should submit the piece to an infiltration process based on cyanoacrylate or epoxy to give it the necessary hardness. Pieces made with cellulose powder can be infiltrated with an elastomer in order to get flexible parts.
The advantage is that it is a faster and cheaper method, although the pieces are more fragile.
For laser printers, when the printing process finishes, we must give it some time until the material finish the polymerization. After that, we can manipulate the part. Certain printers use filaments of PLA or ABS (plastic thread), these melt the plastic building very thin overlapped layers in order to create the object. These materials support the subsequent polishing of the workpiece, unlike 3D inkjet printers.
The advantage is that the pieces are more resistant, although the process is slower and more expensive.
Another 3D printing technology works by injecting liquid resins and curing them with ultraviolet light. It is acrylic-based photopolymer with different physical and mechanical properties: variety of flexibility, elongation at break, strength, colours, etc. It is characterized by its precision and surface finish, which makes its application in tooling very appropriate. The pieces are fully cured at the end of printing process and there is no waiting time, but we must remove printing media with a jet of pressurized water. This technology has been the first to achieve the injection of two different materials in a same printing, allowing the creation of digital materials with properties “on demand”