As some of you might have seen in one of my posts, I usually resort to DIY solutions for my Leitz (and other) lenses - plastic vitamin bottles, PVC tubing, whatever comes handy...
For the collapsible Summicron and Summitar I have metal shades that probably came from some Zeiss lens - or maybe even as a Russian "aftermarket" accessory - marked "42" on the outside, and slips also on my Jupiters... I'd like to have a better lens hood, but at the prices I see on the 'net, I sincerely doubt it - I could get another camera for the price of original 35 or 50 Summicron Leitz lens hood.
So, it's plastic pill bottles and other household items, and Xacto knife, and some black tape

My wife doesn't throw away small plastic bottles and caps any more - she just hands them over to me, for my stash... I'll always find a new use for those
Downright ugly, but they work...
Anyway, here's the photo again...