I was inspired by a DIY using a Pringles can as a gobo between the on camera TTL flash and a macro subject:
Use a Pringles Can as a Cheap Diffuser for Macro Photos
I decided I could improve on this and came up with my own (picture attached below).
Just rubber band your diffuser of choice on the end of the can and good to go.
What's nice about this design is there is no light leakage/loss from the back (it is reflected forward). Also it stays in place very well without any rubber bands--just by the friction of the cardboard against the camera flash.
UPDATE: I am going to play around with various angles on the end of the can.. Make on can where it is 90 degree angle and maybe another one inbetween. Maybe this angle isn't the best? But this one does make the light go straight down (or so) when camera is angled down a bit.
Last edited by geekette; 06-23-2011 at 12:32 AM.