I started by curating photos I have taken for each individual person based on their lives and hobbies. I chose four that looked good together and printed them 4x4 (50¢ each) at the local photo shop.
I then used some basic white ceramic tiles (20¢ each) and painted a coat of Mod Podge right onto the glossy part of the tile and laid my photo flat. I let them dry for about an hour, then did another layer of Mod Podge right on top of the photo (it dries clear), followed by three layers of clear lacquer.
This project does take a few days since lacquer needs about three hours to dry in-between. But since they are waterproof, they can be used as coasters or displayed in the kitchen/bathroom without worry.