Whoa, this is so Twilight Zone. I logged in to ask nearly the same question. But, after re-reading I realize you want to sculpt your face mold and then attach it to the project and I want to use a lifecast.

I'm going to ask my own question on a new post, but if you had a mold that would let you cast the face and immediately remove the mold, perhaps you could place the pliable, wet face on the project and use tools to smooth the face edges into the background. Maybe add some gee-gaws, curlicues, baby leaves to camouflage the seam a bit. That's how we would fix a damaged wedding cake: Just add fancier icing!

Good luck!

Grancru,

I'm not sure if this is what your talking about but here goes: I made a square planter this summer with a face on each side. I used a plastic face mask I picked up at Hobby Lobby. I pressed the tufa in the masked. Then I placed one hand on the front and back of the mold, flipping the tufa filled side of the mask into my left hand. I'm right handed. Pulled the mask off the fresh tufa and gently flipped tufa again into my right hand so the face was looking into the palm of my right hand. I made some scratch marks on my planter where I wanted the face, placed the face on the side of my planter. Smoothed out the edges into the planter while holding the face in place for a few mintues. I did that four times for each side. Here is a picture of the planter. Please send pics if you give it a try.
{{gwi:65968}}

SereneSeen