I wanted an easy way to release Mentos into a 2 liter soda bottle. This holds 5 Mentos (more than enough for a 15+ft fountain) and has two 1mm holes for a paper clip to fit through to keep the Mentos from falling. A screw head easily attaches to the two liter bottle with a tapered nozzle on the opposite end. Tie a string around the paper clip. Pull the string to drop the Mentos into the soda and start the reaction. A second or so later, soda will erupt out through the nozzle. I recommend using 2 walls and PETG as a material (stronger and more water tight). Have fun!
Designed using TinkerCAD.