Ink for Pawprinting?

So I've decided on my first tattoo...the pawprints of my sweet baby girls.
My question is, how do you even take a cat pawprint? What ink should I use? I don't want to use anything that may hurt them if they lick off anything I miss during clean-up. Has anyone tried this?
I've looked all over the internet, but found nothing.
Thanks!

The Discovery Store has the perfect item for this: Discovery Pets Pawtographs Kit

http://shopping.discovery.com/stores...atalogId=10000

I got one for Christmas and love it. The ink is under a sheet of plastic and NEVER touches the animal's paw... it just uses the pressure to transfer the ink onto paper, etc. Decent price too.

Perfect! Thank you tons!

Just gotta say, that's the CUTEST tattoo idea ever!! I've already got a nittany lion (Penn State) paw print tattoo on my left ankle, but I'd definitely consider getting "pawed" by Oliver and my pup at some point in the future too!