Spray paint is not really an option, I wouldprefer a metal one, and I paint would last too long (unless the camera is just sitting on a shelf, which it is not!)
I've had a quick look on Ebay. There are some metal contax replicas on there, but in different sizes.
As far as I know, the Jupiter is 40.5mm, but I take this to be the thread size, not the size of a slip on cap. What size would I be looing for (or model of Contax lens, as most listings quote the lens type rather than size)
Cheers for any help