Run a stud finder over the ceiling in the area where you want to put the compartment. Place masking tape at the stud then move to the other side to find the next stud. Place tape there as well. Between the two marks is where the compartment should be located.
Cut a circle in the ceiling drywall a little wider than your fist or the size of the objects you want to hide. It doesn't have to be a perfect circle, as long as you can reach into it and put things out of the way on top of the drywall. Cover the cut edges with masking tape so that drywall dust does not float down and reveal your hidden compartment's location.
Slide the end link of a decorative chain over a 24-inch-long steel rod and center it. Glue the link down with contact cement so that it won't shift after hanging then wait for it to dry. Liberally coat the two ends of the steel rod with contact cement then poke it lengthwise completely into the hole. Maneuver the rod so that the ends of the rod are crossways and directly over the support beams on each side of the hole and the chain is hanging to one side of the hole. Set the rod down on the support beams so that the chain dangles freely. The glue will bond to the beams and hold the rod in place.
Screw the clips to the ceiling for the medallion. Once attached, the outer rim of the medallion slides onto the clips. Fill the inside of the medallion with foam rubber or some other insulation material. Pull the chain through the center of the medallion then slide the medallion up to the ceiling and attach it to the clips to cover up the hidden space.
Attach a container with a hanging plant to the decorative chain. You can use either a live plant or an artificial one. Remember that you will have to water the live plant; otherwise, people will wonder why you have a dead hanging plant in your home.
Remove the plant and un-clip the medallion to gain access to the hidden compartment.