Here's my DIY Climbing Line Throw Bag Launcher Air Canon. It can be charged with a compressor or hand pump. I can launch a 10-12 oz. throw bag well over 100 ft in the air if it's fully charged at close to 150 psi of pressure. If greater height is required, I'm sure that using an 8 oz throw bag would launche another 20 - 30 ft higher.

Trying to keep my cannon as safe as possible, I chose to use pvc and galvanized piping. Sense the barrel doesn't pressurize, I just used 40 guage pvc piping.

Here's what you'll need to build your own air cannon throw bag launcher.

Barrel: 1-1/2" x 2ft pvc pipe
Barrel reducer: 1-1/2" pvc coupler
Barrel Reducer: 1-1/2" smooth pvc reducer to 1" female threaded

1" male to male threaded nipple (Quantity = 2)
1" brass ball valve
1" galvanized reducers to 1-1/2" (1" female thread to 1-1/2" male thread)
1-1/2" female thread to 2" female thread
2" x 12" threaded galvanized pipe
2" galvanized end pipe
threaded schrader tire valve