Have you ever wished your 3D printer could print with paste, but don't want to buy an entirely new machine? Well, an Italian group called +Lab has come out with a design for a 3D printable attachment which enables you to hook up a paste extruder to almost any 3D printer out there. Some parts need to be customized for each particular printer. More details on this extruder can be found here: http://3dprint.com/17882/lab-paste-extruder

Below is a picture of the extruder with 3D printed parts: