This paper presents a novel approach that leverages large-scale language models (LLMs) for computer-aided design (CAD) automation. We build a large-scale dataset containing over 170,000 CAD models and high-quality natural language descriptions based on GPT-4.1. Based on this dataset, we fine-tune Code-LLM to generate CAD sequences in JSON format from the natural language descriptions. Furthermore, considering that simple metrics cannot adequately assess the quality of generated objects, we introduce geometric and topological metrics based on sphericity, mean curvature, and the Euler characteristic. Experimental results demonstrate that CADmium can automate CAD design and significantly accelerate the design of new objects.