the only thing i don't know is if there would be enough air pressure to push the ball out, after going through the two bolts.
i have another design that i will start on, especially if this one looks like it won't work,
also on the far right is a back view of the two bolts, the bottom two groves would ride on a track on the bottom of the inside of the body to guide up right for the bolt pin to come in through the top.