My 6 step process to create a stone:

1. Create and print the graphics. I can use a photo or a drawing.
2. Transfer and sculpt the graphics onto a sheet of modeling clay.
3. Pour and cure a silicone rubber mold.
4. Make a frame and pour concrete over the rubber mold with added stain if required.  Each stone is approx. 1 1/2"- 2" thick.
5. Use concrete stain to accentuate the graphic image in the concrete.
6. Dry and cure the concrete.  Then touch up the graphics with more stain if necessary.  Then spray on an additional protective concrete waterproof sealer to resist stains.