This tutorial shows how create a concave surface on a product bottle. It specifically takes an existing user file and revises it so subdivision surfaces and boolean subtraction can be used to effectively create the surface.
Videos 1, 2, and 3 are about revising the bottle geometry to create predictable results. These show how to adjust the resolution, position and accuracy of the source geometry.
Video 4 covers revision to the oval object used as the boolean subtraction source and begins the subtraction process. If you want to skip right to the modeling phase of the concave region, start with video 4, specifically at the 4 minute mark.
