No, the Contax hasn't been made since the early 1960s, and Zeiss Ikon ended all production in the 1970s. Third-party production of nearly all items (except for occasional lens-mount adapters for Leicas and a small number of lenses from Cosina) ended long, long ago.
Your best bet is to go to a leather store -- like a company that sells saddles and such -- and see if they can custom make you a strap. I think that would be your best hope.
Either that, or coming upon some old "new" stock of cases with straps.