This Ursula costume was made from a pattern for a long strapless dress. Just cut the top curved instead of straight across and made it about 4 feel too long. Cut the tentacles out and used a different fabric to make the underside of the tentacles.

I sewed them together and stuffed. I put hangers in the tips so i could bend them.  Bought the lavender shirt from walmart and sewed into the dress.  Used kids modeling foam and ribbon for the necklace.  Went trick or treating and met 2 little Ariels that wanted their picture with me. It was great !!