Pulled the background from a high-res screenshot of the ending video from Portal 1. Made the numbers in Photoshop
EDIT 4/18/12: Installed the face into a silver clock. I like it better. Might try a white clock next.
Edit 5/15/12: I'm selling these clocks for $25 + shipping! You can buy them directly from me (PM me for information) or they're listed in my Etsy store! [link]