When its wet it would be like trying to mold ecto plasm. You can carve it and sand it though. I havn't done any great detailed work with this, but my skulls I made in a mold always require some excess to be cut off.
Mr. C, your talent never ceases to amaze me.There is actually a phantom time just before it solidifies when you can (with gloves or a stick or something) pull and push it smooth. That's how I did the neck and shoulders of this guy: DSCN8746.JPG (image)