So ,do you have an orthopod with whom you are well acquainted or
friendly? Maybe you could weazel some casting material from him/her?
Vaseline and wrap is all you need! You can also order the plaster
gauze from Sax.
There's another idea, although, it would not be actual 3-D sculpture for
the evening of your show. What is it called when artwork is temporary -
starts with an "E." My mind isn't working, but with all the talk of
Andy Goldsworthy, I immediately thought of that word because his work
doesn't last...Jancy would know. Anyhow, after having my fifth graders
make cast sculptures of their hands (this was a cast of one hand doing
something in conjunction with the other hand; other hand was drawn as
backdrop for the casted hand. for example, playing the piano, painting
nailpoish, holding a palette and a paintbrush, a computer keyboard, two
hands together making shadow puppet, etc.) they painted their hands and
made them look like different animals, birds, insects, orchestra,
wrestlers. I used a book about handmations. Then I photgraphed the
kids. They and their parents loved these! They had a ball doing them
and it only took one class period. Just a suggestion.