I wanted a small softbox for my Nikon SB-800 flash that is still small enough to carry it around.
The main part slides over the flash head and has also has a hole for a M3 screw and nut to clamp it down if it sits to loose (works great for me without that). For the inside I used aluminum foil as reflector (one side of the foil is a bit more dull, I used that side). I also uploaded a PDF with a printout template for the Reflector (but leave one side a bit longer so the 2 ends overlap). I glued the foil to the paper cut it out an then glued everything inside the box.
As a diffuser I use a tissue and it works great but maybe I am going to replace them with a piece of cloth or photo gel. To provide a better fit and easier switching of the grids I sticked a piece of foam rubber where the grid goes in. Sits a bit tight like that but it won't fall out.
UPDATE: Added 4 different grids for now, one with 60°, one with 46°, one big grid just for softbox use without directing the light and the frame only.
Maybe I am going to buy a Yongnuo 560 (since its quite popular for cheap flashes) and make another version for it.
License:
Creative Commons - Attribution - Non-Commercial - No Derivatives