This site has a bunch of fantastic DIY carnival games and activities. including this simple GUESSING BOOTH.
Ping Pong ball Nerf targets--easy to make with some weighted water bottles and ping pong balls. We definitely have the nerf guns to do this!
The easiest way to make a giant Plinko board for school carnivals or backyard fun. How to make a Plinko board.
Halloween carnival game Carnival circus games - Duck pond matching game - number the bottom of ducks, get 3 tries, matching ducks wins a prize.
Bear scout adventure Grin and Bear IT: This site has a bunch of fantastic DIY carnival games and activities. including this simple KNOCK DOWN game. All you need are disposable cups and a cute sign!