Thermoplast Extruder Variations

Design: Materials:

Barrel:
 Machined out of a brass bolt. 
 Aluminum has been used successfully.
 Combination of stiff copper tubing and copper plate brazed together was used by forrest higgs.
Orifice:
 Mechanical pencil tip was reported to have heating problems.
Barrel dielectric material:
 Furnace cement is now the officially recommended material.
 Both High-Temp JB weld and bar-b-que paint degrade after a hundred hours or so.
Pump:
Insulator:
 Originally designed to be made from PTFE (Teflon
 PEEK (w/o fiberglass reinforcement is reported to work)
 Concrete has been reported not to work (tried by vik, who still hasn't supplied details)
 Drywall mud (shrinks and cracks horribly, tried by John Gilmore)