Shaping Light: Light Modulation Using 3D-Printed PETG

Abstract

This thesis investigates how parametrically designed, 3D-printed Polyethylene Terephthalate Glycol (PETG) surfaces can be used to modulate light in controlled ways. The research examines how material translucency and surface geometry influence lighting effects such as subsurface and layered scattering, directional reflection, and perceptual variability. A computational methodology generates sculptural reliefs and textures in digital models, after which fused deposition modeling is used to study PETG’s plastic deformation during printing. Most 3D printing applications are framed as end-stage production methods, valued for their precision in translating between digital models to physical outputs. However, these approaches do not consider the material’s unique qualities that could be observed beyond strict slicer software parameters.

While much of the research has focused on 3D printed ceramics and clay, studies on plastic printing beyond slicer constraints remain limited, leaving PETG’s material behaviour during printing under-explored. This research frames material behaviour as central to the design process, treating it not as a limitation but as a design driver. In this study, print layers are intentionally revealed, while textures with irregularities are investigated for their potential to produce a wide range of optical effects. Through an iterative process, a series of light-modulating screens are fabricated, and their optical qualities are systematically studied. Findings from the study are applied to produce full-scale light fixture prototypes with varying lighting effects that promote user engagement through tactility or adjustability. Luminaires are developed as both adjustable and static systems, enabling the study of controlled and fixed light behaviours. The work positions these material-driven and light-responsive systems as a framework for integrating perceptually dynamic, user-engaging lighting into architectural assemblies and everyday spatial use.