3D printing involves building a model in a container filled with powder of either starch or plaster based material, that’s been used to support the deposited material for the object itself.
An inkjet-like print head shuttles apply a small amount of binder to form a layer. Upon application of the binder, a new layer of powder is sweeping over the prior layer with the application of more binder.
The process repeats this procedure until the model is complete. As the model is supported by loose powder there is no need for support. Additionally, this is the only process that builds in colours.