Certain fictional or mythological characters traditionally carry tridents. Examples include Poseidon, the Greek god of the sea, and the devil as popularized with horns and tail. Costuming yourself as one of these characters doesn’t take a lot of money if you’re steeped in do-it-yourself traditions. A Poseidon costume might require a lot of silver or gold spray paint, and dressing as the devil might cost you some for red and black material or paints, but making a trident accessory for either of these isn’t difficult.
Draw the bottom part of a trident onto cardboard. While you want a rectangular shape more or less, remember that a trident’s shape is curvier.
Cut out the cardboard bottom of the trident and glue it onto the wooden dowel or broomstick.
Form the flexible steel wire into a cone shape, with the bottom of the cone to attach to the cardboard and the tip of the cone as the tip of the trident’s tine. Make three of these and attach them to the cardboard by twining the wire around the cardboard.
Wrap the trident with three to five layers of extra thick aluminum foil. Use the foil to shape the tips of the trident’s tines into little hooks to match the authentic trident shape.
Cover the trident with duct tape to make it a bit sturdier and to provide a better base for the spray paint.
Spray paint your costume trident gold or silver for Poseidon and red or black for a devil.
Some pictures of Poseidon or a devil's costume might help you visualize a trident more clearly. Library books would have these pictures, or you could find some online as well.