I know there's some guys on here that like to make their own stuff, and even a few that use DSLR's so I thought I'd share this...

http://www.instructables.com/id/How-...on-D-90-Digit/
Follow the link for complete instructions...
introHow to make a fish eye lens for a Nikon D-90 Digital SLR for $16
I got the inspiration to do this Instructable while reading another Instructable that accomplished the same "fish-eye" effect using a PVC reduction pipe and an entry door viewer.

There was concern in the prior Instructable about around scratching the lens so I wanted to solve that problem in my easy to build fish eye lens as well as make a version which is easy to use, remove, etc.

I decided to modify the design by using an existing camera attachment which would easily mount to the camera and comes with most Nikon lenses.

The secret to my design is to use the lens shield as the attachment platform which allows the fish eye lens to be easily attached and removed from standard lenses while enabling a hands free experience.

The lens that I am using in the shot below is a Nikon 18-105mm VR lens. It came with the kit when I bought my camera.