3D printing is where you take an object that you have designed using CAD software and turn it into a working model using essentially molten plastic.
The 3D printer works by putting down multiple layers of plastic at, in the case of the printer below, 0.01mm at a time until the model is complete. This can take a few minutes for a small scale model, a few hours to a medium scale model and DAYS if you are printing something huge.
The printer of choice to start with is very much the CTC. It is not a direct plug and play but it does give you the oppurtuinity to get into understanding how printing works.
If you wish to have a go with 3D printing try buying this.