"饼干模型切割刀" can be translated as "biscuit/cookie mold cutter" or "biscuit/cookie shape cutter".
Here, “biscuit” and “cookie” are interchangeable in this context, both referring to the baked treat. “Mold” or “shape” emphasizes the tool's function of creating a specific shape for the biscuits or cookies, and “cutter” indicates that it is a cutting tool.