Here are the plans that I drew up for my Wrap-around flash diffuser. It is designed for the Canon 430EX Speedlite but could be slightly altered to be used on many different flash guns.
If you build one be sure and post some pics back in this thread so we can all see them. I would really like to see what others can do with this design also. Have fun!!
Looking inside...I used a piece of aluminum foil placed in the center of the inside layer of vellum.
Looking inside where the flash is inserted.
Front angle view..I use an old Stroboframe flash bracket I had laying around to mount the flash.