[Donut]

Limit switches definetly recommended for physical stops over pots. We had a problem last year with a pot rotating with our arm, causing one side to only shut off when it hit the limit switch, and preventing us from turning in the other direction because we designed the code to stop if it hit a certain pot value or the limit switch. A locked arm was pretty close to useless.

On the note of a gate to stop balls, you might want to use a pneumatic or servo instead. It won't be a massive amount of weight to hold back so either of these should work, if you already have pneumatics you might as well use one more (that's what we're going with).