The Survival First channel on Youtube recently posted this video of a DIY secret compartment nightstand. After removing the top of the nightstand, they attached two small hinges and a latch mechanism. Then they added a shelf inside with the help of some wooden blocks.
When the lid is closed, no one would be the wiser that there was a secret compartment under the top. When lifted, there is plenty of room to store a gun, weapon, medication, jewelry or any other valuables that are better off kept out of sight.