hmm i dont see why you would need a machine gun
it is perfectly well possible to do the double slit experiment in a class, if you use a continuous laser. Unfortunatly, with which you show the wave properties of light. to show the quantum nature; you can make use of the photoelectric effect (which einstein used to postulate that light ALSO has a particle nature), or you should use a single photon in the double slit experiment. This is i think not possible with simple equipment.
Bo