Preamble to my question:
I was told by someone at Star-K that since soap is not food, it really doesn't even need a hechsher. For example, he told me that even though Brillo pads are not kosher, it doesn't matter, even if Brillo uses a beef tallow as the soap stablizer. From the FAQ page of brillo.com:
Q. Do Brillo Steel Wool Soap Pads contain animal products?
A. Yes, the soap in Brillo Steel Wool Soap Pads is made from natural beef tallow.
With that preamble, my question is: could I, l'chat'chilah, use my crock pot for a soap making project with my kids.
I would take leftover bars of soap and melt them down using the slow heat of the crock pot and then set them in molds to make new bars of soap.
(I haven't done anything yet. I'm too afraid in case the answer is no. I don't want to treif anything up.)