The recipe:

100 g arrowroot powder
100 g baking soda
50 g SLSa
100 g liquid surfactant*

* I prefer to use Super Mild Surfactant Blend™ from Ingredients to Die For
INCI: Sodium Lauryl Sulfoacetate (and) Disodium Laureth Sulfosuccinate

Depending on what liquid surfactant you use…you might have to modify the recipe a bit.  You’ll just have to give it a go.  Using the Super Mild Surf Blend, I get a mix that is like bath bombs.  If I wanted more of a dough then I almost have to double the liquid surf.  I’ve also used DLS Mild from The Herbarie and at the usage rate above the mixture was more dough like.  You’ll just have to play with it.

Here’s a video!

Confession: I so didn’t let mine sit long enough before unmolding because I wanted to finish the video so they crumbled a bit. Let yours set up and you shouldn’t have crumbles! 🙂