What is the Halachic status of Breadboards on Pesach? Are they considered Matzoh since they are flat, or Chametz since they are breadboards?
Mishnah Berurah (308:116) rules it to be permissible as long as it is not moved.
הוא דף המונח על השלחן כדי לשום עליו הלחם וה"ה מפה הפרוסה וטעם ההיתר הוא כיון דלא מטלטלו בידים.
This is a board which lays upon the table in order to place bread on it... The reason this [breadboard] is permissible, is because one will not move it by hand.
Consequently, the Talmud (Pesachim 37) argues about this very issue of whether a shape prohibits.
אמר להם אפשר יעשנה בדפוס ויקבענה כיון אמרו לו יאמרו כל הסריקין אסורין וסריקי בייתוס מותרין
He said to them: It is possible for a woman to prepare this matza with a mold, and she could set it immediately, without delaying the baking process. They said to him: People would fail to understand the distinction, and they would say that all shaped matza is prohibited, and yet Baitos’ shaped matza is permitted. Consequently, the Sages rejected this distinction, and prohibited all forms of matza shaped in figures on Passover.