I just started looking into this reprap stuff so I may be out to lunch here. Would a hypodermic needle work for this? I checked here :
[en.wikipedia.org]
It looks like there are several id's one could work with. I would expect most people could get access to these locally too. If the length is too long you could probably cut them somehow.
They need to be all metal, and the narrow end needs to be very short, ~1mm. Otherwise the pressure needed to extrude gets very high. It is possible that they could work though.
