We talked a few times in the past about the various conversions of late 1970s Super-Nuovo Campag brake levers to so-called "aero" cable routing. (Of course this is generally a dumb idea IMO, but here for the sake of talking about styles of that era)
Anyway, there is an eBay auction with some decent photos of the Eddy Merckx Co. version of that customization:
Item # 280116770860
Dale Brown
Greensboro, North Carolina USA