I only thought of it, Shac: Don Goldberg actually made something of the idea.
Stand by for another useful device. My M3 has received secondary minor surgery from DG and is now in California, from where it will be brought to India in a traveller's baggage. This procedure is necessary because Indian Customs have decided to harass me by going against their own rules and those of all civilisation.
It is possible that the M3 will have been equipped with another of my admittedly brilliant ideas: a cigarette lighter worked by rotating the rewind knob, the flame emerging from the tripod socket. The Leitz five-letter code for this is FLINT, though I understand that BACCY was also considered.