Choose a wooden piece of furniture that has a concealed gap of at least two inches between the base and the floor.
Use your hand-held jigsaw to cut a compartment in the base to the size you need.
Remove the square of wood.
Use a pencil to draw around one half of the hinges on one edge of the wooden square.
Use the hammer and chisel to remove a depth of wood equal to the depth of the hinges from the center of the marks.
Fit the square back into the base of the piece of furniture and mark the position of the hinges on the cut edge of the base. Remove the square again.
Draw around the opposite half of the hinges on the marks on the edge of the base so that they match the hinge shape cut out of the square and chisel out a depth of wood equal to the depth of the hinges.
Screw one half of each hinge chiseled out spaces in the wooden square and the other halves to the spaces in the edge of the base.
Screw the latch mechanism of the childproof magnetic lock to the edge of the wooden square farthest from the hinges. The secret hinges hide your compartment, but to make it secure, you need the secret latch of the childproof magnetic lock.
Screw the other section of the latch to the edge of the base so that it corresponds with the position of the mechanism on the square.
Close the compartment by pushing the flap shut and use the magnetic key to open your secret latch.