If I understand, you want to press the lure into the clay and then use HS3 to make a side of the mold. That is actually the way we make two piece molds. We then remove the clay, treat the HS3 with a mold release, then pour the second side.
Check out
www.makelure.com for the tutorials about it.
If I do not understand you, well that is what Mike and Larry are for, to correct me. LOL