This setup is simple enough to make that the photos are self-explanatory. I scoured every shelf of my supermarket for a food container that would be suitable as a diffuser. It’s simple, self supporting, cheap, produces perfect lighting, and even acts as a little corral for wee beasties.
With most photography, especially super-macro, you want the light from the flash to be unnoticeable; no white bright spots or shadows. Your subject should be bathed in light rather than shocked with it. A diffuser disperses directional light from a flash and makes it look like it’s emanating from all around. The ultimate example of a flash diffuser is clouds. On a cloudy day, the bright sun (flash head) is directly above the clouds, but once it filters trough the cloud layer (plastic diffuser), everything is uniformly lit with no shadows. The diffused light created by this almond milk container is deliciously smooth and creamy. It works perfectly well for my setup; dual Nikon SB-R200 flash heads.
What if you’re using a single flash head?
Don’t worry, got ya covered homie. For those of you using a single flash positioned overhead, you can use the same principle and type of container, but with a few different cuts. Cut out one complete side of the container so that one of the four sides is now open. Now in a side that’s next to the one you just removed, cut a window just like mine. In other words, as opposed to the upright diffuser that I made, you’re just making a horizontal version that lays on its side.
The cogs in your head are probably already turning of other containers that you could use. Milky colored, translucent materials work best. You can even apply a light coat of white spray paint to get the desired level of diffusion. A gallon milk jug cut in half should work well, as would a white plastic lamp globe cut in half.