I just had a big thought. I had my after school art class make a plaster
craft cast of a student several years ago. We casted the front part first
and then her back. Next we did her face like making a mask and the the back
of her head. We put it back together and it still looks pretty good. You
could cast a person with their arm up and it can be reinforced with wire or
chicken wire and then try to drape the dress with plaster, add the crown and
mount it on a block.