CadQuery/cadquery ? reverse-engineered prompt

Build me a Python library for parametric 3D CAD modeling that feels simple to write and easy to customize. I want to be able to describe parts in short scripts, make shapes like boxes, holes, fillets, lofts, and assemblies, then export them to common CAD formats like STEP, STL, and DXF. It should work well as a headless library, but also have built in visualization so I can inspect models in a notebook or a simple viewer.

Please include a few clear examples and a basic docs setup so someone can get started quickly. If you need current details for the CAD kernel or visualization pieces, look up the latest docs online and follow the usual Python packaging and testing practices. Make it feel like a real open source project people could install and use for engineering or design scripts.