The benefit to being an aunt is you can show up with sugary treats and the supplies to make a "weapon," without any questioning of your parenting technique. Fortunately the ammunition for this launcher is edible and soft, ensuring serious harm was unlikely.
When I spotted this Marshmallow Launcher on the Real Simple website, I knew my niece and nephew would love to help test it out. All I had to say was "marshmallow launcher," and my nephew, niece, and son were at the table. Would they come running as fast if I said "Brussels sprout" launcher?
Load the cup with a marshmallow and pull back to launch! My nephew immediately decided if one marshmallow is fun to launch, a handful is even better. He was disappointed in the explosion as the marshmallow just toppled over the rim of the cup. He did clean up the mess, by consumption. The physics teacher of my previous career had to resist going into a lecture on Newton's Second Law of Motion and Elastic potential energy. The kids got the idea through experimentation. More stretch, more boom. More marshmallows, less boom. More marshmallows?? Yes, please!