This is a simple laser light effect for a disco, outdoor advertising, as well as at home, in a cafe ...
The thing is very simple and everything can be seen from the attached drawing. Mirrors (smaller than a centimeter), everything else is attached to a bent stick from the designer on plasticine, chewing gum, glue ... The batteries last for several hours. Important - the angle between the shafts of the motors is close to 90 degrees, the mirror on the shafts is crooked by 3-5-15 degrees. Result: a classic “Lissajous figure” (epi- / hypo-cycloid) is drawn on the wall or ceiling, with a certain number of petals, it spins all the time, and the number of loops depends on the unevenness of the motors, and changes as the batteries discharge. For children and those who have not seen the oscilloscope - “Wow, how cool!” Gathers in half an hour. For the "advanced": the batteries can be the same - do not forget that the pointer needs 4.5 volts, and the motors you get ... For the "very advanced" - the pointer consumes ~ 40 milliamps, and what will you provide them with - Your business (you just have to turn on the pointer and two motors in series and parallel) from an external 5v source. Do not forget to put the device in a solid case and say that you bought for $ 300 :)) Here are photos (with different exposures) of the operation of this laser light effect.
In this design you will need two small coolers from an old computer. We glue the mirrors on them with super glue. You ask - Where to get the mirrors ?! - I will answer in almost any stationery shop selling Chinese sharpeners with mirrors, and accordingly a laser pointer. Then everything is clear without words!