launcher designs

What are some really good catapult/launcher designs? I designed a gear system that can route the power from 10 motors to any function, at two speeds, and I want to be able to launch stars into the far zone.

you could always do a choo-choo, such as this one, https://www.youtube.com/watch?v=XkkuTIwcB48
or a slip gear such as this one https://www.youtube.com/watch?v=oD4C5mueFhI or somthing like xlr8’s which you can find on the forum