Yeah real nice Jack, is that the 5D?

It's actually cheaper to buy a ready made light-box mate.

You get the things off FleaBay for like next to nothing and it includes lights.
http://www.ebay.com.au/itm/50x50x50...457549?hash=item41a8d5ca8d:g:njsAAOSw7I5TtQXI

I use one of these and they work great for my macro stuff.

A while back I was given instructions to make a light box - it's a bit fiddly but if you want I can E-mail to you on word doc.

Hey, just one other thing reading your post, you mention wanting reach and have suggested the 100mm.

Mate, if I could make a suggestion - have a look at the 135mm F/2.0 L. I have used both lenses and pick up the 135mm as a matter of routine now.

Extremely sharp and fast and a dream to work with in low light conditions!

Horses for courses of course.

EDIT - Just reread your post and I see you're upgrading your macro lens to the 100mm - yep ! (read a bit quickly)
Even still, if you have a chance have a try of the 135mm lens and compare.

Possibly able to knock two birds over with a single stone

Flies look awesome , really like the Copper John style jig fly.