Studies of model insects have greatly increased our understanding our animal development. Yet they are limited in scope to this small pool of model species: a small number of representatives for a hyperdiverse group with highly varied developmental processes. One factor behind this narrow scope is the challenging nature of traditional methods of study, such as histology and dissection, which can preclude quantitative analysis and do not allow the development of a single individual to be followed. Here we use high resolution computed tomography to overcome these issues to 3D image numerous lepidopteran pupae throughout their development. The resulting models are presented in figures and supplementary videos taken for a single individual throughout development. They provide new insight and details of lepidotperan metamorphosis, and allow the measurement of tracheal and gut volume. Furthermore, this study demonstrates early and rapid development of the tracheal system – while unresolved in the caterpillar, tracheae become visible in scans just 12 hours after pupation. This suggests that there is less remodelling of the tracheal system than previously expected, and is methodologically important because the tracheal system is an often-understudied character systems in development. In the future this form of CT-scanning could allow faster and detailed developmental studies on a wider range of taxa than is presently possible.