Have a Tattoo Booth at your PTA / PTO Halloween party - kids love them!
How to Make a Nerf Spinning Target - Fun game for a Nerf birthday party! Great boredom buster too. This would be great for a superhero party, too.
Hook a duck wedding game
This site has a bunch of fantastic DIY carnival games .and activities. including this simple GUESSING BOOTH.Love the guessing booth idea as students come in and LOVE the signs.
Make your own fake-barbell for the strongest person alive. Hooray for DIY costumes!