I think I saw this idea on Pinterest. Gotta love that site!
We used white tiles like these. Then printed out photo's on photo paper and cut them to the size of the tile leaving a little room around the edge to see the tile. Then glued the picture to the tile.
Then covered the picture/tile with resin. Just following the instructions in the kit I found at Amazon here. It's helpful to use a brush you can throw away. I also used a straw to blow out any bubbles and then let them dry for a couple days. They came out great!
The final step was to put some feet like these on the bottom so they don't scratch.
They were really fun using family pictures!