My child spray painted a huge paper mache bumble bee he had made in kindergarten and I saved, so it looked like a fly, complete with metallic googley eyes and velcroed it to the back end of the saddle pad. He dressed as a policeman and carried a giant flyswatter we found at a Mardi Gras supply and he and his horse went as the original Swat team. The police uniform came from a goodwill type store. Entire costume was under $15 and that included paint.
Some horse people change their horse, they change their tack and discipline, they change their instructor; they never change themselves.