From RepRapWiki

Fields Metal Syringe

A fields metal syringe would most likely be based off the Syringe Based Extruder.

It would use the heating attachment and be heated to the precise temperature needed to extrude fields metal. I think theres a writeup of this somewhere on the wiki... hope i can find it.

-- Main.ZachSmith - 11 Feb 2007

More Info

An experimental Fields Metal Syringe is described here Syringe_Pump_Metal_Extruder