I'm acually in the process of making a small "Lathe" from scraps of Balsa, a few Motors, and a 9-volt battery. I currently have the beginning set up sort of a "Grinding Wheel". Soon I'll post how to make it on Instructables(http://www.instructables.com/).
I have an idea, just spin the pvc you're planning on turning into a plunger on a lathe or other thing that will spin it. Get a piece of sandpaper and fold it in half, but don't crease it. As the pvc is spinning, put the sandpaper folded side down onto the pvc until it sands a channel the perfect size for your o-ring. Let me know if anyone tries/has done this.
I figured that if you wanted to get good distance and height, you would use a 45 degree angle. The furthest up you would angle it before losing distance would be somewhere around 22.5 degrees. Any further and you start to lose distance but gain height
I see you point, and nothing sounded mean at all, i just come up with lots of random ideas and post them. The other reason that i have so many ideas is that i build robots.
As of typing this, i got an idea . A nerf sentry gun
I'll get to working on it as soon as i can, because i still have school
I'll probably have it dont by the end of the week.