[Kevin Sevcik]

I haven't tried that or any of these ideas, but yes, that does sounds like a way to check ball density. Other options would be a roller on a piston with a reasonably heavy spring and a potentiometer to measure the maximum displacement of the piston. Or a bar with rollers on it and a strain gauge to measure how much the bar bends. Or really anything where you have something springy pushing against the ball and you measure how much your spring moves. I think the important thing to remember is that you'd need to take the measurement on the same point of each ball. So you'd need to either position the ball and measure it, or look for a maximum or minimum in your measurement.

Which all sounds complicated, so building a shooter that more immune to different ball densities might have been a better idea. I know I'm starting to think we should've given catapults and centrifugal arms a little more credit in the design matrix....