I have it on very good authority that Langsett cycles( the original maker in Sheffield England) made bomb sights in secret under the shop during the war for Lancaster bombers...i believe these were possibly precision made versions of the wooden 'y' piece with nails in them. also 'Terry's made loads of small steel components not just cycle brackets/ stop-watch clip's etc but also parts for wash tongues etc...
Steve Chambers
Chesterfield
England