Plumbing my garage for compressed air...

Sounds way overboard with all the drops. If it were just me I'd stub it in and just use a hose. The compressor won't run more than one tool at a time very well anyway.Then just get a good quality hose that stays flexible even in cooler weather. It will last for twenty years if you disconnect it when not in use. And PVC would work fine. I have watched them test different plastics at Amoco Labs and some of that stuff will take enough pressure to blow up like a balloon before it gives.It wouldn't surprise me if the piston or pistons? in your compressor are plastic. For more than one line I just put a simple tee together with a male and two females and there you have it. I will also use a small portable tank in-line if I need more than 100 feet, like up on the roof or something. Also you live where it is cold so use big wire if you put it outside because it may have start up issues.