https://techcrunch.com/2018/11/06/this-3d-printer-squirts-out-wet-paper-pulp/

Like a kid shooting spitballs, designer Beer Holthuis has figured out that sopping wet paper is the best material for making mischief. His 3D printer, a primitive RepRap clone that literally squirts out huge lines of paper pulp, is designed to allow artists and designers to create more sustainable 3D objects.

According to 3DPrint.com, Holthuis was searching for material that wouldn’t create waste or increase plastic pollution. He settled on ground-up paper. By extruding the wet paper he is able to create a thick bead of pulp that he can then build up to create decorative objects.