Dog tail

I completely forgot to mention last night that I would like Crab the dog to have a tail. And a tail that can wag! Any engineer or budding engineer out there that would like to tackle this project? I am thinking it needs to be motorized, but maybe some sort of pull cord will work. Micaela was thinking something along the lines of those wooden segmented snakes. And I would like a golden retriever type tail. Possibly this could be a project between a couple folks, maybe even father/son. Let me know ASAP.