The Big Four started life as armatures made of willow, newspaper, bits of junk and some clay to make it smooth, all covered in clingfilm.
Upon this I built up layers of strong brown paper strips and PVA glue, letting each layer dry and stopping when the shell seemed hard enough. Holes were drilled in adjustable safety helmets so that the beetles could be bolted onto them.
Legs were made from one continuous length of wire to give strength, wrapped in newspaper and bound with masking tape. The “undercarriage” of legs was glued to the shell before painting began. (Real beetles' legs are attached to the thorax - some artistic licence here.)
Smaller ladybird models were made similarly using layers of paper and PVA glue. The bees were mostly made using layers of plaster bandage and are detachable from their one-size-fits–all magic gloves by the use of Velcro.