Check out this video that shows the making of the Lydian Drakon for the film Percy Jackson: Sea of Monsters. He actually never made it in the film, but according to what is stated below, that was probably a good thing for purists of the book.
Here’s look at the development of the Lydian Drakon character for the film PERCY JACKSON: SEA OF MONSTERS. The concept started as a scary 6’5″ frilled lizard man and became a 4’6″ comedic sidekick. The character continued to shrink until it wasn’t in the movie at all. That doesn’t negate the precise sculpture ADI’s Aki Ikeda, the paint scheme of Mike Larrabee and the application by Bill Terazakis’ talented Canadian makeup crew featuring Maiko Gomyo, who herself is no bigger than your thumb.
Thanks to Hypable for the tip!