Cheers Bantha, I get what you're saying regards the thread method, never thought about the thickness of the nozzle though, good point.

I saw another RepRap video just after I posted that, one called RepRap Pro which has microlayering.  Sounded pretty nice and they say you can get perfect vertical edges with it.  Would be cooler still if it could print in rubber, would be fantastic for making molds with!