This technique is called Faux Alligator Skin. You can click the name for a tutorial from Jackie Topa. I didn't have an alligator stamp - but I did have a snake. It's from Stampin' Up! 1991. My friend Kim gave him to me, along with like 500 other stamps that got this whole obsession started! *Hi Kim!* So, I made snake skin in lieu of Alligator Skin! Mind you, I don't know if snake skin really looks like this - because I want nothing to do with a snake. So just go with me on this one. :)
And here is a purse I made with the same technique. I guess the purse could be Alligator, or Snake, or cheap patent leather? Fun!
Short directions: Take a piece of black card stock. Cover it with VersaMark ink. Sprinkle black embossing powder all over it. Use an object to "draw" lines in the embossing powder. Then apply heat with your heat gun until the embossing powder has melted. Done!