It is no bake clay (even after sitting for over a decade it is still soft and oily, which is why it is covered in dust), I found that out the hard way. The first version melted in the oven.
I made it somewhere between 15 and 20 years ago, so I do not remember the exact brand of the clay. It is not actually clay, it is some kind of polymer. It is supposed to be air dry, but I never fully hardened.