Draw the outline of your prop on white foam core board with a soft lead pencil so it does not pierce the paper coating. Cut out your shape carefully with a craft knife. Save the larger scraps of foam core and set them aside.
Paint your prop as desired for the show. If you are going for a cartoon style, draw bold black boarders around the colors. Speak to the lighting and set designers about which colors will work best. Some colors, such as greens, may not show up well under certain lighting. Allow the paint to dry completely.
Find a scrap of foam core from Step 1 or cut a new piece into a 6-inch by 6-inch square. Cut a horizontal oval that is 4 inches wide by 1.5 inches high out of this piece. Begin about 1 inch down from the top and make sure the oval is centered. Save the square, as this will become your prop's handle and allow for easy carrying on and off the stage.
Heat up a hot glue gun and apply hot glue to the bottom half of your square. Press the bottom half of the square against the very back of your prop, near the middle.
Fold the top half of the square handle (the part with the cut-out oval) back until a crease forms in the foam core's paper coating. If the foam core is too stiff, score the handle about an inch below the oval cutout with your craft knife and then fold the handle along the scoring.
Label the back of each child's prop with his name in permanent marker so the props can be sorted easily and returned to their owners if lost.
Ask the children to practice holding their props, using only the handles. Add new handles if necessary to facilitate easy carrying.