There is a great article over on DIYPhotography talking about how to make a reverse macro ring for a nikon. Basically it looks like they are taking the end cap off of a lens and a spare filter and gluing them together.

I have some concerns regarding this method:

• a plastic/glued connection to hold an expensive lens to your body?
• Alignment issues, if that isn’t properly attached it could mess with the focus and the picture a bit
• I am a big fan of DIY but it is only $10 for a reliable reversal ring on ebay

The final results look good though:

Please read over the article yourself at: http://www.diyphotography.net/diy_reverse_macro_ring

1. Another DIY Reversal Ring but for a Canon | MacroReverse.com Says:
   July 8th, 2009 at 7:25 am

   [...] wrote last time about a nikon diy reverse macro ring adapter.  I stumbled apon a Canon version over on instructables from user jeoncs where they use an old [...]