make him a cardboard crown, hyou could decorate it with jewels, these could be brightly coloured buttons, bits of cheap plastic diemonds, you just buy a cheap plastic kiddies bracelet or necklace and take the beads off, use some cheap bright coloured fabric to make a kings cloak for him, if you know someone whos handy with a sewing machine, you could make it out of old curtains or throwover.