Kinder Egg "Grenade"

thingiverse

Print this container. Fill 1 teaspoon of sodium bicarbonate into the container and insert it into a Kinder Egg toy container. Add vinegar to the lid of the toy container. Secure the toy container tightly without mixing vinegar and sodium bicarbonate. When you're ready to launch the "bomb", give it a swift shake and toss it away. This is purely for entertainment purposes, nothing hazardous here, just a big pop. The acid in the vinegar reacts with the sodium bicarbonate, producing enough carbon dioxide to blow off the lid of the toy container.