Did you see the release post on Lisa's blog for PTI...here is the link.
Wanna know how she did it? Keep reading for my tutorial and enter soap into the search box on the left sidebar to learn more fun ideas for soap crafting.
Stamp and Soap Tutorial
For soap like Lisa did you would just lay your stamp into the soap mold facing up toward you. Fill with clear melt and pour soap about 1/4 to 1/2 way, next top off the soap mold with a colored soap or white melt and pour (this will become the bottom of your bar).
Now when you do this you will get a cavity on the top the shape of the stamp you put in (including all the extra space).
Go back very carefully with the melted soap color you want to use and just fill in the spots where you want the contrasting soap and leave the extra space empty.
If you are going to use your PTI stamps for this REMOVE CAREFULLY they do tend to rip easier then rubber.
Clean them off right away the residue can damage your polymer stamps.
This is fun, she makes it out to be easy but for a beginner using a stamp with your soap is advanced and will take some time to work out your details. Just don't become discouraged if you don't find it "pitifully easy" the first time out.
Fact is I enjoy more stamping on Tissue paper and embedding it into the top of my soap bar. Tutorial for this here.
Happy Stamp Day, God Bless!