Thanks for the link Willy.
Here is something I put together for you:
edit: I pulled the zip file and I'm just posting the .png files straight to the web... see the posts below for FX Chain skin assets that may be saved and used freely. I made two rotary knobs out of images of African masks but they are small and may be too small.
Anyways, this might be useful to get started... if you want to comp something up and send a screen shot of your chain maybe we can tweak some details or do the other elements to make a nice finished look.
I hope you have fun with it.
best regards,
mike