Main character heads were initially sculpted in either Plasticine or clay . Once the general aspect had been finalised , this served as the template for a silicone rubber mould . This was coated with Bondaglass ( fibreglass mixed with resin ) and enhanced with Bondapaste , a putty @-@ like substance , to accentuate contours . The Bondaglass shell was then fitted with a solenoid , leather mouth parts and plastic eyes , as well as incisor teeth – a first for a Supermarionation production . Puppets known as " revamps " , which had plastic heads , portrayed the supporting characters . These marionettes started their working lives with only a mouth and eyes ; their faces were remoulded from one episode to the next . Particularly striking revamp moulds were retained and , as their numbers increased , photographed to compile an internal casting directory .