With a few notable exceptions, the majority of objects removed from a 3D printer bed are fashioned using plastic. But plastic has a nasty habit of ruining our environment at the end of its useful life. Designer Beer Holthuis looked for a more sustainable alternative, and built a 3D printer that extrudes paper pulp to build three-dimensional objects.
Holthuis has revealed precious little about the project, other than that the pulp is mixed with a natural binding agent so that the layers stick to each other as they're built up from the base. An electric motor drives a belt that turns a wheel to push down a plunger into the cylinder housing the raw pulp material, this forces the pulp through a green tube at the bottom and over to the print head.
The basic open printer is made from ply, with a moving print bed and an extruder that rises vertically and moves across rails horizontally. The paper to be pulped can be sourced from household waste and, though the print resolution is not going to win any contests against plastic printing machines, the resulting objects do have a certain rough and ready, unfinished charm to them. And Holthuis reports that they're surprisingly durable when dry.
When the printed objects are no longer needed, they can themselves be recycled, or perhaps even repulped.
You can see the Paper Pulp Printer in action in the video below.
Source: Beer Holthuis
P.S: Better air dry it, or that stuff will start mildewing quickly.