I than painted over the soap. Be sure to really coat the frame in paint. Make sure to cover all the soap.
After it was dry, I too fine grain sandpaper to the edges. The paint practically melted off, it was so easy! Be carefully not to get too carried away or you won’t have any paint left 
That’s all there is to it! Here is my final product, I’m so happy with how it came out.
I also tried this on plastic by just sanding it first. Lightly scoring it helps the paint to stick.
Lastly, my jewelry dish. I hope I gave you some ideas to start soap distressing on your own!