Here’s how you can do it. Before you get started, gather the following supplies: Take a piece of 4-inch Schedule 40 PVC pipe ...

You can also buy new pipe; it's relatively inexpensive. Lowe's sells 10-foot lengths of schedule 40 PVC Charlotte pipe for ...

The build uses PVC pipes for both the barrel and the air ... which is nicely within the 280 PSI rating of the 2″ Schedule 40 PVC being used. Though, as they note, the connections in the design ...