Here are some gadgets that I, Star Knight, have created effectively. All of these are non-harmful if used with responsibility.
The Shocker Glove- this bulky glove has the special property of conducting a harmless amount of electricity. It is a good alternative to a stun gun and looks cooler too!
The Concussionist- this uses soundwaves that amplify each other by having simular frequencies and creating a loud burst of sound from them. Due to the nature of sound's longitudinal waves, it is best to wear some serious sound-mufflers. Using this once or twice usually does the trick and gets crime running, covering their ears.
The Anti-footing Slip Plastic- Exactly what it sounds like, this plastic is like any other, but it's what you put on it, an extremely slick oil, that makes this "gadget" what it is. This is great for when touble makes run for it from the crime scene. With them slipping on the plastic, you can get closer to capturing them if that is your goal.
Cesium Smoker- A classic smoke bomb using cesium (or rubidium) and water. Encased in a small plasic ball, the initial explosion of cesium will be absorbed and used to open the ball and water vapor will pour everywhere! It is, of course, hard to hold the target since you can't see yourself, but they will run.
Sodium/potassium firebolt- These almost act as popping, fizzing sparklers. They are used simular to the cesium smoker but tend to be less of a smoke show and more of a frightening fireworks display for a few seconds. Too many of these on a target could set them on fire, so be warned! Remember, we are heroes without powers, not pyromaniacs.
Camo Blanket- This is nothing special, it's just a dark cloak that can blend in with forest and alley scenes with low light. I will soon have a blanket that can bend light and give a better measure of stealth.