Lay down plastic drop cloths over the floor, and tape them to the walls to prevent the process from getting material on the other surfaces in the room.
Mix drywall compound with water. Add water, and stir the compound with a drill mixer to blend the two together. Stir and add liquid until you have a thick milkshake consistency.
Fill the hopper of a paint sprayer with the mixture.
Adjust the nozzle to a fine spray so you can coat the ceiling evenly and smoothly.
Spray a small 3-foot-square area with the mixture, and then stop.
Swirl over the surface with your tool of choice to create a pattern. Some examples of tools you can use include a wire brush, a bristle brush, a flat-edged trowel or a notched trowel.
Spray a new section of ceiling after you've swirled the first. Repeat the spraying and swirling until the entire ceiling is covered. Be careful when spraying so that you do not overlap a swirled area with more material.