Not just any Cylon: one that might have existed in an era of steampunk. You know, a Charles Babbage, Jules Verne, pneumatic brass and crystal Cylon!
Imagine a Cylon Heavy Raider crashes in the 1800s somewhere on Earth. Only a single Centurion survives, and it's heavily damaged. Realizing its only chance at survival is to use the tools available, it repairs itself with the materials of the era.