I’ve made a lot of plaster molds of my tiles over the years so I thought it might be useful to show my easy mold making process.
1. Attach tiles to a silicone baking pan using slip.
2. Put on some nitrile gloves and a dust mask. Line a bucket with a leak proof plastic bag.
3. Add two parts water to a bucket.
4. Add three parts pottery plaster to the bucket.
5. Mix the water and plaster together until smooth.
6. Pour the plaster into the pan. Wiggle the pan so the air bubbles come to the surface.
7. When plaster hardens, remove from mold and clean up edges and add fine details.
8. Find a place to store them.

Very well described process! 👍🏻