Yeah, this is an interesting topic.
I have indeed found a very cool lens hood online:
Sadly, it is not for sale currently (and hasn't been in some time).
While there are no current photos on the site, the wayback machine snapshot of this product page includes photos of it:
That thing would be pretty much perfect for my little canon 35 ltm f2 and also your summicron.
I wrote the guy who designed it a couple months back and he told me that apparently the plastic that he used for the shade was discontinued (by shapeways? I'm not sure). Until there is a substitute, production is on hold. Maybe if you write him as well he'll take it as an increase in demand and provide a solution...