Hi All,
Sorry if this has been asked, but I would like to see the different ways shops have been plumbed for air, what diameter piping, and material. Please share and sorry if this is a duplicate.
Michael
I hate to be that guy, but this is one of the most frequently asked questions on this board.

If you page back a few pages you'll probably find some recent discussions. You could do a search, but one problem with the software used for this forum is the search doesn't work for terms that are three letters or less (like 'air'.) However, you can use Google to search the board and get much better results:
How to Google Search Within a Website using Site:Search
Step 1: Go to Google.com. Duh.
Step 2: Enter site:
www.website.com search term into the search box.* *Pay attention to the subdomain (the letters that precede a domain name, like
www., blog., or info.) you enter. ...
Step 3: Refine your search.