Just in case somebody needs rare-sized hoods or filters, e.g., for the Summarit 50mm f/1.5, and doesn't mind a third-party item, check out HeavyStar (HeavyStar Photo Gears Home Page). They make a vented metal hood for the Summarit 50mm f/1.5 that would actually stack onto an E43 filter, and supply an E41 to E43 step up ring with it. So I can use 43mm filters between the step up ring and the hood. I've also purchased a 39-43mm step up ring for a Summicron 50mm f/2 Dual Range, so I'll be able to use the same filters and hood with it as with the Summarit. The hood itself comes with a cap, and caps for 43mm lenses are also sold. The prices are reasonable. The hood (incl. step up ring and cap) for the Summarit costs USD 24.88); the step up ring for the Summicron, USD 6.95. The hood and step up rings seem to be aluminum painted flat black.
Regards,
Richard