Extruders for 3D printing / additive CNC.

Extruders pump out a material which will self bond after some short time in order to form a solid mass. Most often, this is accomplished with a plastic or other matierial which is heated by the extuder head, or "hot end" which then cools after it is ejected. A spool of plastic filament is pushed into the hot end by the extruder much like an automated version of a hot glue gun.

See also:

• http://www.instructables.com/id/Hot-Glue-Gun-Extruder-for-Your-CNC-Machine-or-3D-P/ Low resolution, very basic, but still useful extruder made from a hot glue gun, stepper motor. and a big gear with some rollers.
• http://www.hotends.com
• http://www.seemecnc.com The "Steve's Extruder"
• http://www.makerbot.com