Looks good! A couple suggestions...
1.) What kind of bumper do you have behind the piston, and how well does it fit in with that male adapter/bushing combination?
2.) A simple way to cut down on pilot volume (although a shorter piston would probably be required) would be to replace said male adapter/bushing combination with a 2" threaded plug. Make
sure it's a pressure rated one (you'll have to look at Ace probably).
3.) Going with the above suggestion, change the pilot valve to a 1/4" Q.E.V. Just drill and tap a 1/4" hole in your plug, thread in the Q.E.V., and add a ball valve and male auto coupling to the Q.E.V.'s pilot. There are more ergonomic ways to do that but I'll leave that to you. With a properly "taped" piston and some grease, a 1/4" Q.E.V. should be plenty to pilot the valve.
4.) In the future, you can "butt up" all of your fittings (talking specifically about the female barrel adapter and tee) by trimming down the length of your bushings slightly and removing the lip at the front. You also could probably use a 2" female adapter for more barrel selection (just use another bushing in the female adapter).
See here for what I'm talking about...
Just a few suggestions... none of them really necessary. I agree that this launcher would look better with paint, but that's not really necessary either.
Oh, and you can also tape off your fittings and pipe with masking tape before gluing to reduce primer stains. I usually tape them off around the fitting and pipe, and then use a razor blade and some tape to tape off the lips of fittings, although if you're butting the fitting up, just leave the lips alone (maybe file/sand off any markings or mold marks so they butt up completely).
But sorry for all the rambling, the launcher looks great!
