The complexity of modern software systems necessitates robust modeling tools, with UML Class Diagrams serving as a cornerstone for representing static system architecture. However, manual creation of these diagrams is a significant bottleneck, being both time-intensive and prone to error. This paper extends our framework for automated UML generation to tackle the intricate challenge of Class Diagram synthesis. We propose a dual-model pipeline where a lightweight LLM (LLaMA 3.2 1B-Instruct) generates detailed technical specifications, which are then translated into PlantUML Class Diagram code by a powerful reasoning model (DeepSeek-R1-Distill-Qwen-32B). This process yielded a novel dataset of 5,000 samples, each comprising a technical specification, a PlantUML code block, and a corresponding diagram. To ensure architectural integrity, we deploy an automated multimodal validation system using …