Volta’s Electrophore 

This item is composed of a polystyrene base that you can electrify by rubbing it; on this base there is an aluminum disk with insulating handle.  If you bring the disk near the electrified base several times, and each time you connect its upper face to the ground, it is possible to store big quantities of electricity on it, to the point that you can obtain electric discharges up to 1 cm long.