You can't have too much of the fun snap explosive stored, because the explosive is actually very easy to detonate
The explosive used in fun snaps is impossible to aggregate of large quantities because it has a tendency to self detonate under its own weight. The compound is called silver fulminate. It has very little practical value since its extremely sensitive to heat, impact, pressure, and electricity.
A falling feather, a drop of water, and a small static discharge can detonate silver fulminate. It was first prepared in 1800 by Edward Charles Howard. The only purpose it has ever been able to be used for is to make novelty non-damaging noise makers for children.