Any shaped cake pan would work, with 2 parts, clamped together while baking, the smaller part near the top of the cake. When cooled the clamps can be undone, the top part removed, and using a long bread knife, the rise on the top of the cake could be sliced off, thereby leveling the cake. And there's your sample! You get a better sample (corners tend to be the driest part of the cake, anyhow). When frosting a cake properly you don't want the sides or bottom compromised, because crumbs drag into the frosting. The leveled side of the cake is where the filling goes, between 2 layers, or it can be the bottom of the single layer cake. This would be a great tool to assist with leveling, which is normally done by just turning and slicing, and is not always perfect.