Creating the mold

Warning: The steps described below involve those horrible things called chemicals. Whenever using any of the products listed herein, make sure to ask for copies of the Materials Safety Data Sheets, read them, and follow their directions. You will notice on this page are a couple of pictures. It's winter in Chicago, so I don't do this work outside, but I do have a room in the house which has a fan in the window to keep it at "negative pressure," so the fumes are unlikely to make it into the rest of the house. Whenever I am working in that room after doing this work, I have a respirator, fit to my face and tested, which I wear to make sure I don't inhale them. Always wear gloves (of course), as well.
It's not inherently dangerous to work with these. Nothing here is so toxic it's going to kill you right away. However, prolonged exposure will do Bad Things to your system. A good respirator (from a occupational health dealer, NOT your local hardware store) is less than $50, and worth every penny. I tend to use broad-spectrum filters, since they should catch just about everything I would be exposed to, rather than having different filters for each product.