Thanks! It's always good to know people like my stuff. You should teach my parents how to do that
Anyways... One of us seems to be misunderstanding something. An end cap goes on the end of a pipe and caps it off, and you can't attach anything else to it. My understanding is that you will cap on end, and use a reducer on the other end to go from 2" down to 1", so you can use your elbows. Am I missing something?
Regarding the valve... The best thing would be a piston valve... But they are hard to make and considering this is your first build I don't think it would be a wise decision. They are especially hard to make with metal, and it would be a shame to have a high pressure tank and a plastic valve. Your gun is only as strong as its weakest part.
That said, you can use a QEV... But the ones that can handle high pressure generally stop at 3/4", which is not big enough for your 2"x24" chamber. However, you could always use a 1" diaphragm-style QEV, which would be pretty effective and not that expensive. There was a thread all about them very recently that I'm sure you could look around for.
Before I go any further I just wanna say your chamber is large enough to launch golf balls at a considerable distance. Are you sure you want to use it for a 1" caliber launcher? For such a small launcher perhaps you should use a smaller chamber and save the big stuff for WHEN you decide to go bigger
But I mean... Being that this is your first gun, maybe you could just go with the ball valve just to get the hang of things. You could always spring load it, which would probably double the power and definitely give you better stability and accuracy
Once you get tired of that, a QEV or piston valve will be inevitable
