Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for proft or commercial advantage and that copies bear this notice and the full citation on the frst page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specifc permission and/or a fee. Request permissions from Permissions@acm.org. TEI ‘22, February 13–16, 2022, Daejeon, Republic of Korea © 2022 Copyright is held by the owner/author(s). Publication rights licensed to ACM. ACM ISBN 978-1-4503-9147-4/22/02…$15.00 https://doi.org/10.1145/3490149.3502252 ABSTRACT This pictorial unpacks the prototyping journey of Digestive Tumble - a tangible system that demonstrates the processes involved in the human digestive system. The system aims to support awareness of our digestive processes and help users to make informed decisions about their dietary choices. Digestive Tumble consists of nine modules, where the modules visualise a unique stage of the digestion. The system represents the digestion of fve major food groups: grains, meat, vegetables, fruits and dairy through colourful tokens. Users interact with the system by inserting tokens representing their meal. These tokens transform into colourful beads, which then traverse through different modules to show the digestion of the given meal. We refect upon the steps involved in visualising an internal bodily process through a tangible system. We hope that our design refection will inspire future systems on visualising other internal bodily processes to support body learning through everyday refection. INTRODUCTION “You are not just what you eat, you are what you absorb.” - Thais Harris. The human digestive system is one of the most important systems in our body [4]. It plays a vital role in converting food into nutrients, which the body then uses for energy, growth, and cell repair. Understanding the digestive system is the frst step in raising interest in topics related to gut health and helping people to understand how their dietary choices impact their health and wellbeing [23]. While there exist several textbooks and websites describing the mechanism of our digestive tract and the factors involved, these mediums offer a static mode of learning where visualizing the operation of the digestive tract and movements of the food is diffcult [3,35]. To overcome this, researchers have designed physical [14,15,28,43] and digital [1,7,13,24] replicas of the digestive system to support awareness through interactions. For example, Perkins e-learning program utilizes a series of tactile visualizations such as Knitted Digestive System [15] to help the visually impaired people understand the arrangement, sequence and structure of the digestive organs [14]. Body Odyssey [7] is a multimodal virtual reality based experience that allows individuals to learn about the digestive organs by letting them crawl inside the human body and explore the organs through visual, tactile, and auditory sensations. InsideOut [24] explores a playful representation of the digestive tract through the ingestion of imaging capsules and representing the data on an iPad. Finally, a large model of the human digestive system is also displayed at the MONA Museum in Australia [5] that shows the digestion of food from intake to excretion with realistic visuals and smells. These works however, offer general information related to the human digestive system with which an individual may not be able to relate on a personal level. Moreover, it could also be diffcult to apply such factual knowledge in an everyday routine because of the subjectivity and diverse eating practices of any individual [37,38]. Besides, these works focus on creating awareness about the anatomical structure of the digestive tract, and give less emphasis on the processes that happen inside one’s digestive tract, which we consider as a missed opportunity. Understanding different processes may help in understanding how different foods get digested, which in turn could prompt individuals to eat a more diverse diet. As such, there have been limited attempts on representing digestive processes for everyday refection, which we explore through Digestive Tumble. Crafting Tangible Interfaces for Human Digestion: Unpacking the Research through Design Prototyping Journey Rohit Ashok Khot HAFP Research Lab, School of Design, RMIT University Melbourne, Australia rohitashok.khot@rmit.edu.au Jason Ng HAFP Research Lab, School of Design, RMIT University Melbourne, Australia jason.ng@rmit.edu.au Deepti Aggarwal HAFP Research Lab, School of Design, RMIT University Melbourne, Australia deepti.aggarwal@rmit.edu.au Authors Keywords Digestion; Human-Food Interaction; Tangible Interaction CSS Concepts • Human-centered computing • Human computer interaction (HCI) • Interaction systems and tools