I went to Lowes to get the rest of what I envisioned I would need.
The guy who gave me the inspiration for this project used aluminum foil and glue to add the reflective surface to the inside of the box. I found some aluminum tape at Lowes. It was $7.58 a roll so I figured why not.
Here's the breakdown on what I spent:
Rubbermaid bread keeper $5.47
Package of #8 screws and nuts $ .97
Package of #8 machine screws $1.18
Wing nuts $2.36
Fender washers $2.30
Aluminum tape $7.58
Materials total $19.86
Not included in this list is the speed ring from one of my softboxes, black gaffers tape and some black foam core. I always keep gaffers tape and foam core around, both black and white.
I started by drilling 4 holes in the lid of the bread keeper for mounting to the speed ring. Then I cut out a hole for the flash head. I cut the hole using a knife, making it slightly larger than my largest flash head. I mounted the screws using fender washers on either side of the lid using a regular nut on the outside to keep the screws in place. Then I attached the speed ring using the wing nuts (for easy assembly in the field).
Next, I wrapped the inside of the bread keeper with the aluminum tape, leaving the flat side open. I also wrapped the inside of the lid with the tape.
I wrapped the outside of the box with 2" gaffers tape to minimize light spill. I made some flaps out of tape for the flash head opening. Once again to minimize spill.
I attached some velcro strips on the outside of the box to be able to mount flags. I made the flags out of some black foam core and attached velcro to those also. I made the strips long enough to be able to adjust how far the flags extend. I made sure that the flags would fit inside the box when not in use.
Here's the finished box with the flags attached.
I plan on using the box for rim lighting and for table top set ups. I may add a layer of diffusion to the open part of the box which would be easy to tape to the inside or the outside.