I'm not sure how good brass is for conductive material - I think that it is a mixture of copper and something else. So it should conduct electricity OK. Might want to hit up the "The Puck" thread here on ECF - it gives details on how to build one. I've built 4 so far. Traded one out for some sucky V4L KR808 cartos.
You could also try the 6 volt but know you'd have to have a higher OHMs on the wire and more wraps in your coil. I'm still playing around with mine too - if you can, get a 5 volts (or 4,8 volts, depending on what batts you use) and give it a shot before trying to go with 6 Volts. I got my batt boxes from the local Radio Shack - $2,- apiece. I also use Ni-Mh rechargeables, no Li-On batts for me. Each batt is 1,2 volts, so it's easy to play around with stuff by stacking them...
But you are getting a Line - you probably won't want to get anything else after that!!!
I did mine coz I'm too freaking broke to get in line for a Line, LOL.