The film was produced by clay animation using character models each about the size of a wine bottle. The models were first constructed using plasticine before pouring Carbog, a solid material used by mechanics, into moulds to form the bodies. They were then painted to appear like plasticine, and real plasticine around wire was used for the arms. Elliot said he chose to use Carbog since models made from just plasticine would require more maintenance. Some characters had replaceable mouths made of hardened Sculpey clay that were attached magnetically to the faces to reflect different facial expressions; Harvie's model had more than 30 separate mouth shapes. The design of the models was influenced by Elliot's tremor, since he needed them to be relatively large and easy to manipulate. He made the models' eyes particularly large "to fully express the character's emotion". He intentionally left fingerprints in the plasticine when manipulating the models to remind the audience that "what they're seeing is tangible, tactile and it's not generated through a computer". He was assisted by Sophie Raymond and Michael Bazeley in constructing and modelling the characters. The sets were largely constructed from wood.