There was a thread about metal pens, this was done with out using brass tubes, just drilled with a C drill and reamed to .244, the ends were chamfered and the nib installed, the transmission was a wee bit tight so I had to open that end up to .245 which was still snug, but it fit, I did this on a metal lathe and this is actually the first pen I ever made, we decided it would be one of the more useful tools our students could have. It's 6061 aluminum with gunmetal fittings,