This looks like a lot of fun (and an simple kit to make) – “This very unusual kit emits random pops and random explosions of bright white light when it is in the dark (kit has a CDS cell to sense the absence of light). This kit produces one of the most unusual “out-of-this-world” effects. Features SCR and CDS circuitry with 3 bright lamps and a piezoelectric speaker. Easy to build and creates a spectacular display. It may even cause speculation as to whether or not it was left here by aliens! We put four of these into a darkened room and the resulting sound and display was amazing! Size of PC board: 2.9″ x 2.4″. Operates on 2 AA batteries (not included). Complete with all parts, PC board and instructions.” – Link.
Cosmic poppers kit