It contains three different lasers. The first is a microwave-powered laser particle beam, the second is a laser-guided high-pressure water cannon, and the third are some pieces of steel wool that have a laser.
When turned on, the microwave-powered laser shoots out a green laser, the water cannon shoots out water, and the steel wool laser shoots out a yellow laser. The device also has the ability to cross the laser beams.
Role in episode
In order to remove a dirty spot on a plate, SpongeBob invents the Spot-Master 6000. Later, when he sets the Spot-Master 6000 on maximum power, the Krusty Krab explodes and the invention disintegrates.
The Spot-Master 6000 may be a reference to the 1984 movie Ghostbusters, in which it is revealed that crossing the beam of their proton-pack lasers will end life as they know it.