Colo is a concept of sneakers designed to correct foot deformities and improve bad walking habits. If untreated, these problems often lead to more serious health issues later in life. The concept is therefore aimed at children between three and twelve years old, while their walking patterns are still becoming stabilized. The design consists of shoes, a smartphone app and custom 3D printed insoles. The main feature of Colo is that its sole is designed to passively track walking habits. The function is based purely on material wear, without any use of sensors or tracking devices. A distinctive curve pattern is produced by layering on different colors of soft plastic, so specific gradients are revealed after regular use. This helps to detect the anomalies in children’s foot development, either visually or more precisely with a smartphone app.