Merrylegs mould, and the model itself is a portrait of Little Prince from the accompanying book, which I don't have. Interestingly, the character in the book is meant to be a gelding, but the mould lacks any male anatomy, so I consider it a mare.
Alongside the marks on her body she also has very scratched up hooves. It all adds up to suggest she's been well played with in the past.
Etching is the process where you gently scrape away the surface paint to reveal the white plastic below. Many tools can be used for this process, but sharp blades like crafting knives are the best, so for this reason you have to be very careful and children should be supervised by an adult. Also, you're only scraping off the paint, not gouging into the plastic.
I did a little bit of research before I started, and I decided I wanted my mare to be a British Spotted Pony. I wanted to keep as much of her lovely palomino coat as possible, so I went for a small blanket pattern with additional spotting on the belly and shoulders to cover the rubs there.
Her pattern probably isn't 100% realistic. Rather than work off a reference image I was trying more to cover up the areas where she was rubbed. I don't think she'd ever be show quality anyway, since her paint has so many blobs, bubbles and flaws in it to begin with. Regardless, I like her.
Oh, and because of how unstable she is on her feet, she's earned the stable name 'Tippy' :)