Yes Robbie Fellows (on CR) did the Campagnolo hoods. I have a set of his on my Gios Torino
It seems that there are a number of Italian producers of the Campagnolo hoods that are highly regarded has taken that niche market.
David has a excellent thread on how to make urethane parts.
For the DIY, the product able to be used is limited to take into account the need for room temperature curing, acceptable shore hardness and relatively long pot life. The long pot life is to allow for the mixing and degassing and then curing under pressure, all in the quest to reduce the appearance and size of unwanted bubbles. I have the vacuum pump (for making leather saddle covers) and I have bought a pressure pot for the pressure curing.
I am not sure the honking rubbers would fit the later curvaceous brake bodies. The GB Standards were more workmanlike in shape. Try that link and see if he will make a set of Weinmann hoods. He was very easy to work with.