The numerous systems designed to facilitate animals’ use of computers often are specific to the animals involved, their unique context, and the applications – enrichment among them. Hence, several development methods have arisen in parallel, largely transposed from the human-computer interaction (HCI) domain. In light of that prior work, the paper presents a step-by-step guide for iteratively designing and constructing interactive computers for animals, informed by the rich history of HCI yet applying animal-centred principles, to enrich animal-computer interaction. For each stage in the iterative design (requirements, ideation, prototyping, and testing), the author reflects on real-world experience of building interactive devices for various animals. The paper concludes with overarching considerations vital for future practice of developing interactive computers for animals. Thus, it serves as a valuable reference and information source for researchers designing novel computer systems for animals.