My name is Heidi. I have an idea for a mermaid costume these are my ideas; take a sack that is big like a potato bag. Cut a hole in the bottom, then try to get a little bag for the fins .Make sure that the bag is big enough for your feet.
To make look like a mermaid fin tape it if you need to.
Then try to get two shells. Make a tiny hole on both sides on each shell.Tie a piece of string on the holes make sure it is big enough for your breast but if your a boy you don't need shells. Then put on the costume and makeup if you want. Trick-o-treat safely!
Thanks to Heidi for this neat idea!