I wrote last time about a nikon diy reverse macro ring adapter, so I felt it would be good to do the same when I stumbled upon a Canon version. I came across this on instructables from user jeoncs where they use an old 58mm Hoya Filter and a Canon EOS Tmount with some mighty putty to fabricate a diy reverse ring.  Here are a few pictures:

Sample Picture of a Peanut taken with the setup:

Please check out the guide at:http://www.instructables.com/id/SDUUN66FROAANKM

I do have to be honest though here, you can buy a reversal ring on ebay for $10 or less.   I do admire the diy reverse macro photography spirit though and feel it deserves some credit.