The successful adoption of artificial intelligence (AI)-enabled tools in engineering design requires an understanding of designers’ mental models of such tools. This work explores how professional and student engineering designers (1) develop mental models of a novel AI-driven engineering design tool and (2) speculate AI-enabled functionalities that can aid them. Student (N = 7) and professional (N = 8) designers completed a task using an AI-enabled tool, and were interviewed to uncover their mental model of the tool and speculations on future AI-enabled functionalities. Both professional and student designers developed accurate mental models of the AI tool, and speculated functionalities that were similarly “near” and “far” in terms of analogical distance from the AI tool’s functionality. These findings suggest that mental models and cross-application of AI tool functionality are readily accessible to designers, offering several implications for widespread adoption of AI-enabled design tools.