ha! When I saw your title, I was thinking "caterpillar" as in the creepy crawly bug type ... not A "CAT"
And to think I used to work CAT.
For your track design what about a variation of bricks and mortar?
BTW ... great picture ... angry sky looking like it's ready to let go with a cloudburst, while the CAT has some good light focusing on it. Maybe a bolt of lightening?