Tools and materials
A peephole, of the model you want, a drill with the right-size bit, cylindrical sandpaper for metal and a screwdriver.

Drill the hole
� When you choose where you are going to place the peephole (normally in the center of the door and at a height appropriate for the user), with a pencil or magic marker, mark the spot where you want to drill. The instructions that come with the peephole usually tell you the diameter of the drill bit you need.
� If the door is solid wood, you will need a drill bit for wood. If it is reinforced, with a metal plate inside, you will need a bit that can pierce this.
� Place the bit and drill perfectly perpendicular to the door and start to drill. Don�t use the hammer option of the drill.

Install the peephole
� If necessary, sand down the edges of the hole with a cylindrical tool, especially if there are shards left from the metal plate, or a jagged point on the surface of the door.
� The poophole is made up of two parts that fit into each other. From the outside of the door, insert the glass part with the lense. From the inside, insert  the part that rotates and screw it in a little bit.
� With the screwdriver, press firmly until the outer part fits in snugly and does not move.
� Touch up with varnish or paint if the surface of the door has been marred during this work.