What valve do you recommend? Also, i'm having trouble finding pipe for the air chamber that is bigger than the barrel. What size barrel does the air chamber have to be? Can it be smaller than the barrel?

What metal exactly to use for the barrel and chamber? What sort of metal pieces do I put together to make the air chamber?

Are you sure air will not leak out near the threads? What should i coat the threads with?

Do I have to weld anything? Or is it just as simple as screwing threaded parts together?

Where can i get all these items?

What kind of metal do I use for the air chamber and barrel? How do I make the metals air tight and seal them together?

Thanks for the reply @jrrdw. I clicked all the links and read every letter and word. The only problem i have is that all those builds are made out of PVC and i'm going for an all metal design.

Before i get any bad comments i could not find a good or reliable build for this anywhere on the internet, let's change that now... OK, so how do i build a metal pneumatic tennis ball launcher that uses air from a compressor or bicycle pump? Looking for the most simple design. (air tank behind barre...