"+George Hahn sure, see my list at http://thingiverse.com/triffid_hunter/things - it's in there somewhere :)"

"interesting. http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html supports your note. brass conduction > by factor of ~4, alloy dependent. then you look @ http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html and see how the PTFE barrels just smoke the metal barrels altogether. who's using metal barrels?

The budaschnozzle (http://reprap.org/wiki/LulzBot/Budaschnozzle#Intro) has a heat sink on it. i to re-design a std mendel carriage to support it. neither my stock mendel nor my lm8uu prusa carriage fit the thing! :$ look forward to having a cool extrusion system"