Using a few bits of waste plastic from the kit iIve come up with 2 methods and wanted to know what you think looks better.
First and easiest is using a flat head soldering iron straight onto the HL plastic.

This looks pretty good to me but it isnt going to be easy to get that "chipped off" look that you see on so many zimmerit coated tanks. Also as Sturmtigers were built onto reconditioned Tiger 1's, and the zimmerit would've been applied to the original tank at the factory, its something a really want to do. So I came up with the second method which is to glue a thin piece of plastic card into the kit first, and then once its dry to use the soldering iron again to melt the zimmerit pattern into it without going too deep into the kit plastic. Once this has cooled its then quite easy to chip off where you want to get that well worn effect.

So which one do you prefer? I dont want to mess about with pastes or fillers and I really like the effect this creates. Its actually surprising quick to do once you get going.
Here's another pic showing both methods. The glued on plastic card is the on at the top.

Let me know what you think.
Nic