Well after browsing a bunch of options i found this can in my truck while cleaning today and thought heck this may work well.I used the small can that they have recently started selling around here.
Here are the steps
1. Measure the pop up flash and cut out with exacto knife ( make a bit small)
2. Cut metal end off of the metal end of the can
3. I used a cd sleeve to cover the end to add a bit more diffusion
4. This works well as the cilider can be rotated and the top is a bit thicker and can offer a bit more diffusion
Here is an example of the difference with and without
WITH STUART'S PRINGLE DIFFUSER