Sometimes a flash needs more modification than a mere card can provide, so I decided I could make a more useful light source with a mini softbox. Naturally I decided to try my hand at building rather than buying, and I came up with this cheap and easy solution. Here's how I did it.
First I started with a small scrap of quarter-inch white foamcore. I used an old studio reflector card, truth be told, and by choosing one good edge and cutting off the bad, beat up edges, my softbox looked fairly crisp and clean, too. I also decided that something in the 8"x8" range would probably be the perfect size, so I knew all I needed was a strip of foamcore at least 8" by 32" (four sides multiplied by 8 inches is 32 inches in total).
Next I measured the size of my speedlight to determine how big to make the small end of the softbox, where it would attach to the flash. It measured roughly 2 by 3 inches, so I cut two pieces to taper to a 2-inch end (for the sides) and two pieces that taper to a 3-inch end (for the top and bottom of the flash). Rather than erring on the side of a box that's bigger than the flash's face, it's better to cut them smaller. A snug fit is much preferable to a loose one. Either way, in the end a bit of gaff tape is the easiest way to affix the softbox to the flash head, and that's how I do it.
With the four sides cut, it's time to piece them together. Gaff tape is helpful here, too. Simply lay out the cut pieces, being sure to alternate between sides (which will be two inches at one end) and the top and bottom pieces (which will be three inches at the end). I laid them out and taped them together with the face up side as the interior of the box. I stood up the box and taped the last seam on the inside and outside. This double-layer of tape may be excessive, but I think it's helpful for stability of the box. At this point, the softbox resembles a pyramid with openings at the top and bottom.
Next it's time to make the diffusion for the softbox. I made an interior baffle as well as the main diffusion for the wide end. The interior baffle will help to diffuse the speedlight even further, making for an even softer illumination from the small box and helping to minimize a hot spot. To create the baffle, I simply cut a square of diffusion material about five inches on each side (frosted gel is perfect) and notched the corners so that when I taped each edge to the interior of the box the corner material wouldn't crinkle too much. Ultimately this made the baffle fit better and hopefully perform a little more effectively as well. It doesn't have to be perfect, after all—it's on the interior of the softbox.
For the exterior diffusion, I measured a square two inches wider than the wide end's opening, but I didn't notch out the corners. Instead, I simply made a one-inch cut at each corner, on an angle. This provides complete coverage of the front of the box, and the notches allow the excess material to fold over and lay flat for taping. No bunching at the corners.
With the box complete, I made some test shots to see how the frontal illumination would be softened. You can see in those tests how well it works. It makes for a unique look, whether you're using the speedlight as the primary source or as a subtle fill. Given how small this speedlight softbox really is, I'm impressed with just how much it softens the light source.
Part of the fun in building things for yourself is experimenting with different approaches to fine tune the results. I encourage you to experiment in the creation of your own speedlight softbox. And if you come up with any great variations, please share them here in the comments below.