On the basis of a laser pointer and a motor, you can make a simple laser level, with which you can set a straight line on the surface.

This will require a laser pointer, preferably more powerful than in my article.The more powerful the pointer, the better the level will be visible on the surface, but here it is necessary to observe safety precautions and protect the eyes.Next, I need a motor, I used a fan from household appliances, removing the blades.We attach a mirror well to the motor.Now we supply power to the motor and the mirror rotates.We point a laser beam at a rotating mirror and a straight line appears on the surface.The motor with a mirror must be installed on a flat surface, otherwise you will not get a straight line.