My solution for airlines in my machine shop. Hard to track down a source for gasPex. Copper has gone way out of sight price-wise. Iron isn't cheap and besides having to deal with a bunch of possible leaks at the couplings and being a bear to route where I needed to route it, I settled on 3/4" 1 wire hydraulic hose. Compressed gas rated to 1,250 PSI and fairly tolerant to higher temps. Cost was $1.76 / foot delivered to my shop. JIC swivel ends were less than $5 each. From the air compressor, I needed to go up into the attic, under a floor in the loft, and then continue through another part of the attic to the point where I came through the ceiling tin and down to the first filter/regulator drop. I installed a tee where the hose came through the tin and branched off to the filter/regulator near the machine tools. I can't imagine that it would have been a pleasant job to fight it out with pipe couplings in the attic. Hose was nice. We ran a fish tape, taped the hyd. hose to it and pulled it to where it belonged. Here are some pics of the project:

 The compressor was set on top of the entryway hall to my computer office. This half of the shop is semi-heated and serves as a parking garage for our personal vehicles.

 A PVC 45° Street elbow served as a shield for the electrical service and air hose where they entered the attic. I added an auto-drain fitting to the compressor since I didn't want to climb up to the ledge and make a mess with draining the water. Purging every time the compressor cycles keeps water from building up and making a mess when it is manually drained. Notice the swivel JIC fittings where the hose hooks. Much nicer than fighting with pipe thread.

Air line is routed close to the ceiling to get to the drop near the lathe. The Tee is mounted where the first drop runs to the filter/regulator. The steel fitting serves as a protector from the sharp tin. Again, JIC swivels are oh, so much nicer than NPT threads, unions, pipe dope, etc.

Close up of one of the air outlets.