And once again we find out that 'what works' for one might not work for the other. Often that's a matter of skills and preferences, but here seems to be quite obvious that some details of the substances got muddled under the guise of 'clay'.
Here that not all clay is created equal. I'm guessing that any clay designed to be baked should work. Neat that play doh works, and that some guys don't use "putty" of any sort.
Hot metal.