Review on 👀 50 Pairs of 6mm Glass Eyes for Art Dolls, Sculptures, Masks, Fursuits, Taxidermy, Jewelry Making - Flatback Option by Michelle Langley

These can work if you need to add them quickly and only need to fire the clay once. Or it can be bypassed if you don't mind wasting a few sentences. My experience with them wasn't great. The white part of the eyes was discolored after the third or fourth bake. After removing the eyes, the substrate became sticky and discolored. This means a chemical reaction between the plastic backing and the unfired clay. This happened every time. The way I've gotten around this is to use a pair to bake with clay and then at the end take them out and replace with a new set.