Produced by a special needle, this magic tattoo appears on your body as an amorphous blob until you make your first contract. After that, it appears as silhouettes of your contracted familiars.

Tattoo Attunement. To attune to this item, you hold the needle to your skin where you want the tattoo to appear, pressing the needle there throughout the attunement process. When the attunement is complete, the needle turns into the ink that becomes the tattoo, which appears on the skin.

If your attunement to the tattoo ends, the tattoo vanishes, and the needle reappears in your space.

From Contract.  You can attempt to convince beasts that are under challenge rating 1/4 to join your cause by casting the spell Speak with Animals as a ritual. If the beast agrees (at the GM's discretion), it becomes a spirit as you form a contract with it and it is added to your tattoo's physical appearance. 

Stable of Familiars. You can cast the Find Familiar spell as a ritual without using any material components. When you cast the spell in this way, your familiar must take the form of one of your contracted beasts.