Silicone soap molds along with latex soap molds were the most common ways to make custom soaps. That's changed. No longer will you have to work with smelly, unhealthy chemicals to make your molds. And you're not limited to one or two molds. You can make any shape mold that you want.

With ImPRESSive Putty. Heat, press, and you have your soap mold. Add letters, shapes, different sizes. The possibilities are endless. 

Here's a couple videos showing how to make soap molds. 

And to show how easy  soap molds can be, here's a little helper.