Anyone have suggestions on making a windscreen for a Shure SM11 lav? http://tinyurl.com/4shh9
The commercial windscreens I've seen are all designed to go on the outside of people's clothing. I need to hide these in a shirt collar. I have two actors walking down the street in somewhat windy conditions. The lavs are connected to minidisc recorders that they will carry in their pockets. Can I just tape a cotton ball over them or something? It would seem like the collar would offer some protection already.

Since this is already a dynamic omni mic hidden under the collar, you may not need any additional protection. Hopefully you'll have room under the collar, these capsules are huge by modern lav standards.
If you do attempt to add some protection, I would make it minimal. You won't have much room to work with anyway and you don't want to create rubbing noises between the screen and clothing. Unstarched cotton clothing is usually pretty quiet.
For a screen, you could use any thin sheet of soft open fiber material.
Cut a small circle of the material and then notch out little triangles from the edge so it will lay flat when folded over the end of the capsule. Secure with gaffers tape.
These mics are already dull due to their design, adding too much protection will dull them even more.

Thanks. These lavs ARE huge, but it's nice that they don't need a power source so they're ideal for minidisc. I have successfully gotten one under a shirt collar before, but the subject was wearing a tie. That made it considerably easier.