Pig skin is used for tattoo practice!

While “plastic skin” exists, many up and coming tattoo artists still practice and hone their craft on pig’s skin. It is much similar to human skin because it allows you to see the needle entering the skin and thus get a better handle on how to control needle depth.

Pig skin is also quite elastic, so it also helps an artist understand how much to stretch to get a good line.

However pig’s skin for tattooing does require a fair bit of preparation. When it’s not being used, the skin needs to be in the freezer to keep it soft. Before tattooing, it need to be taken out of the freezer and placed in warm water for a few minutes. The number of times it’s freezed and thawed does not affect the quality of the skin.

(Source)