Casting a paper wasp nest

Paper wasps build nests using fibers to form a paper like substance.
wasp nest
Inside, they look like this:
wasp nest pragments
wasp nest fragments
I made some foam and paper sprues
and attached them to the nest fragments with masking tape:
sprues taped to wasp nest fragments
These were packed in loose sand (shake gently while doing this).
wasp nests set in dry sand
The molten aluminum was poured in the sprues.
poured wasp nest mold
This is the resulting rough casting:
paper wasp nest cast

This is the back, with the sprue still attached>
back of cast, with sprue