Let's see how to create a sheet metal base flange. First, you will need a 2D profile and then use the flange base tool.
In the control widget, this allows you to control the base flange position: up, middle or down.
Use boundary detection for more complex 2D contour boundary selection.
By moving the mouse cursor inside the contour, a special highlighting appears. The boundary is detected, and the flange base tool can be used.
The thickness can be changed in the properties section of the mechanical browser.