Condor Werke A580 Swiss Army Bike
Technically, this is a restoration, not a custom job, but it's still such a rare bike that it's worthy. Post WWII, the Swiss Army wanted a bike on par with the Germans' BMWs. Condor had been building bikes since the late 1800s, and put together this number, complete with an eight speed gearbox—four for roads, four for more entertaining terrain. The fact that it's virtually indestructible is a pretty nice bonus.
Aaron Miller is the Rides editor for Supercompressor, and can be found on Twitter. He's a little embarrassed to admit he'd never heard of Condor until seeing this bike.