A talk on the utility of 3D modelling to PCB design, and a brief review of where open-source tools currently stand compared to commercial offerings. Having introduced the ideas, and why we may desire to add 3D functionality to our software tools, I will attempt to give a very brief introduction to solid modelling (3D CAD), and compare the requirements for rendering graphics vs. working with engineering models. I would aim to touch upon the subjects of BREP models (vs. surface models), and interchange formats such as STEP (AP203 / AP214), and their complexity.