I had another idea. I work with polymer clay often and you could easily (and inexpensively) make necklaces. Find horse related molds (horseshoe, horse head, etc.) such as for candy making and push the clay into the molds, pop it out, make a hole in the top with a toothpick and bake it as instructed. It can be painted and sealed with gloss, then attach a cord or lace. OR, you could also use a stamp. Make a flattened shape out of the clay, stamp your image, make hole, bake and paint.
This is an example of the stamped technique. I didn't make it, my mom got it for me from Mexico, but it's easy to see it was handmade from clay.
Stella - sweet, timid, elegant, lovely, lively, amazing
Luna - large, unattractive, naughty, adored