This was the system for my chain-link magnetic cups:
1. Cast a 12-ounce glass from Target into ceramic
2. Indent the soft clay casting using the original glass used, so that there is a space where two cups could hug together
3. dig out spaces for magnets to fit into opposite cup walls, allowing for clay shrinkage so the magnets will sit snugly and flush with the surface of the cup
4. Cast this prototype into ceramic again; produce
This sketch hung on my studio wall for the semester, and I'm glad I saved it. When David Pahl took product shots of the CLMCs last month, I played art director and - without realizing it - styled the cups pretty much identically to my original sketch:



Somewhat eerie, but comforting to me as well. I do like when things work out this cleanly.