Add your food coloring one drop at a time (remember it will get lighter as you mix it into your dry ingredients).
Add the wet ingredients to the dry, a little at a time so you don’t get fizzing.
Whisk the ingredients together and press into your mold. I used a stainless steel mold (seen below) and am really happy with it. You can also just form it into a very tight ball using your hands.
Fill both halves of the mold and press them together.
Give it a light tap, and then remove one side. Flip over and remove the other half.
Set it gently aside and let dry for at least 24 hours. This is key so they can dry and totally set. Then, you can package them up.