I have made a lot of flash diffusers in the past, using anything I could get my hands on, from old milk bottles to marscapone pots. They all do a great job, but they don't last 2 minutes when out in the field. I saw this old Apple Airport laying around at Nottingham Hackspace and it immediately hit me that it would make a great solid long lasting flash diffuser.
The results are great, heres how to make your own.
Step 1: Remove the internals.
The white plastic around the ports is a separate piece, but is held in place with one of the screws. So easy to add back in later.
Step 2: Mark and Drill Corners
I then placed the front end of my flashgun onto the centre and drew the outline.
I then found a drill bit that roughly matched the corner radius I had drawn.
Carefully stack up some scraps of wood under the plastic and drill out the four corners.
Step 3: Drill along edges
Assuming the holes are close enough together you can easily cut the remainder with a stanley knife or boxcutter.