Ah, a snow‑shaped rig for a Leica—classic! I once tried a pinecone mount for 1/2000 and the pinecone turned into a snowflake, but I salvaged a rubber gasket from an old cassette for the gasket, so don’t forget a spare. If the camera starts humming, just blame the cold, and bring a thermos; the lens will be jealous of the warm hands. Good luck, but keep a spare shutter release cable in the toolbox, just in case.