There are already a few of these but I wanted to post my own version as im rather happy with my results! :)

The great thing about this project is that you can make it as long/short as you yourself require (longer tube=closer macro) AND it will fit with any lens made for the canon EOS series! :)

one thing to note, if you make a long tube it will allow you to take photos SUPERCLOSE, but your "focus-range" will be minimal, meaning that if the object your taking a picture of has any curves, only a tiny portion will be in focus

Pictures:
http://i.imgur.com/RVrQpgG.jpg
http://i.imgur.com/9VlU3tZ.jpg
http://i.imgur.com/CF0IQI3.jpg
http://i.imgur.com/8w8DIw1.jpg

Things you will need!!

Cover for your DSLR Body
Cover for your DSLR lens, as in socketcover.
A tube of some sort, I used a roll that used to have giftrope on it (anything that dosent let through light can work)
A hot glue gun
A dremel or other tool for making holes in your covers
Black Electrical-tape

*if wanted*
a bottle or other tube to fit over the "lens-extension" to make it prettier :)

Step 1: CUTTING! WOO!!

Use a dremel tool, or other method, to remove the center of both caps, get rid of all plastic that isnt holding the lense/camera.

These caps will be Glued onto the ends of the tube, allowing the tube to fit into your DSLR body like a lens would.
Then the same goes for the other end of the tube, but with the socketcap that allows you to put your lens into the extension.

Step 2: Finding a Tube, Cutting It.

The tube I used was a plastic-roll for giftrope (dont know specific name sorry).
Turned out it was a good fit :)

Cut your tube into a desirable length, to find out you´ll have to experiment with different lengths, thats what I did :)

Step 3: What Happend?!

Im sorry but I got a bit carried away during the project and didnt take enough photos, BUT I havnt done as much as it might seem!

All that has happend here is the following:

1. I glued my two lenscaps onto my tube using hot glue.

2. I cut my tube in the middle , made it shorter, and glued it back together as one piece

3. I used black Electrical tape where I had glued to make sure no light came into the tube

4. I cut a clear plastic bottle and fitted it over my extension to make it prettier. (had to sand down the tube before putting on the bottletube)

5.Painted it :)

Step 4: Inside and Finished Extension

As you can see the inside of the tube isnt smooth at all, and it dosent have to be.

What is important is that there is nothing covering the view for the mirror in your DSLR, and no light coming into the extension, I used alot of black electrical-tape as you can see in previous steps :)

Step 5: Final Product and Pictures!

So here is the final product!

So a check list for your own extension.

Lens is aligned with the camera when fixed to it´s extension (in other words your extension is straight)
Your extension shuts out ALL exterior light

thats pretty much it, hope you all enjoyed this instructable, its my first :)

Pictures:
http://i.imgur.com/RVrQpgG.jpg
http://i.imgur.com/9VlU3tZ.jpg
http://i.imgur.com/CF0IQI3.jpg
http://i.imgur.com/8w8DIw1.jpg

Do check out the links as they are the only way you will see how immense the macro is! :)