Copyright © 2015 ACM. The creative promise of 3D digital fabrication tools is tremendous. However due to the wide range of tools and interfaces, a common static file format called STL is used for sharing designs. While customization tools add creative handles to these digital models, they are often constrained to pre-configured parameters limiting the creative potential of shared digital models. We introduce MetaMorphe, a novel digital fabrication framework that uses a common web-programming metaphor to enable users to easily transform static 3D models into re-formed, re-made, and re-imagined customized personal artifacts. We demonstrate the compatibility of Meta- Morphe with three well-established design interfaces, direction manipulation, scripted-CAD, and generative design. Through a user study with design experts, MetaMorphe reveals that decisions that physically produce bespoke artifacts or encode unique metadata actively affect perceptions of authorship, agency, and authenticity. We discuss how expressive model-building tools such as MetaMorphe enable a cultural shift in 3D design in terms of participation, personalization, and creativity.