Got an old SLR lying around and want to make use of it? How about modding it and making a peephole out of it?

Jared Polin of Pro Knows Photo shows how to install it. All you need is an old SLR and lens and some 2 1/2 inch PVC. And provided you've got the permission to drill through the door, you've got yourself a new old peephole! [Fro Knows Photo via Peta Pixel]