I modeled a few faces for the Mini 13 since the original head looks boring.

Lucky 13 Version: https://www.printables.com/model/929640-lucky-13-face-pack

I painted the holes (the face) with normal acrylic paints.

Faces List:

1- Happy   2- Sad   3-Neutral 

4- Heart Eyes   5-Amazed  6- Raised Eyebrow

7- Naughty    8- Angry