Just a few ideas I'll be working on and thought you may want to as well Answered
https://www.instructables.com/id/Knex-Spray-Shot/ Take that old concept... line a bunch up and turn it into a claymore mine. #2 take that concept extend the mag capacity and turn it into an uzi type sidearm with a barrel to guide the shots a bit for a fast firing all or nothing last resort side arm. #3 maybe turn it into a grenade.
These are a few of the ideas among many other I will be experimenting around with hope I sparked some ideas!