Hi, just to share how I made drop-in color correction filters for my 580EXII. These can be made easily and precisely with a laser-cut cutting template. A x-acto #11 blade is used to cut Rosco sheets around the template over a glass plate. Very easily and quickly done! The drop-in filters doesn't get in the way of any light modifier e.g. stofen, lambency, demb, etc and is a snug fit to the speedlight flash head without getting loose. Changing out the filter is just a few seconds and very convenient without the need for any velcro. Here are some photos of the filters and template, and how it fits the 580EXII.

