Building a Component Registry for Parametric CAD with Python

When building parametric CAD systems, one of the most frustrating challenges is managing components from multiple sources. Your project might need custom-designed parts, standardized fasteners from a library, electronic components for enclosure design, and community-contributed models from a package manager. Without a unified interface, you end up with inconsistent APIs, scattered imports, and code that becomes increasingly difficult to maintain. This article explores how to solve this problem using the Registry pattern - a design approach that aggregates multiple component sources behind a single, consistent interface. The code examples come from a real-world parametric CAD system built with CadQuery, demonstrating how this pattern handles everything from M3 screws to drone motors to Raspberry Pi boards. By the end, you will understand how to design a component registry that supports lazy loading, LRU caching, and graceful degradation when optional dependencies are missing. The proble