First you will need materials. Most of the materials can be purchased localy at a hardware store. I got mine at home depot, But I had to order the ACRYLIC LENS online.
1)4" PVC PIPE (about 6" long,but it depends on your Camera.)
5)1/2" CLEAR ACRYLIC. I got mine online at tp://www.freckleface.com/. I was unable to find it localy, But I bet it would be cheaper.
6) 4" to 3" converter for lens area.
8)SOME SORT OF WATERPROOF CAULKING.