The goal of plasticity is to ensure usability continuity whatever the context of use. This context must be modeled into the system and possibly taken into account to adapt the final application. The difficulty to handle plasticity for 3D applications comes from the lack of solutions for developers and designers to model and take these constraints into account. This paper introduces new models designed to deal with plasticity for Virtual Reality (VR) and Augmented Reality (AR). These models are implemented in a software solution: 3DPlasticToolkit. It aims to provide a solution for developing 3D applications that can automatically fit any context of use. This context of use includes a set of 3D hardware and environmental constraints, such as user preferences and available interaction devices. 3DPlasticToolkit includes tools for modeling this context and for creating application components independently from it. We propose an adaptation engine based on a scoring algorithm to dynamically create the most suited 3D user interfaces according to the context of use at runtime. We use a furniture planning scenario to show how these adaptations can impact interactions and content presentation.