A profile consists of one or more hatches and/or contours. Hatches are simple lines. In a bar, hatches are expanded to two dimensional surfaces. You can combine any number of hatches to create any pattern.
Contours consist of several hatches which are connected at their end points. These endpoints thereby become corners.
If the option Close Contours Automatically is enabled, the contour is automatically closed when you click on the first point or very close to it. The first and last point are merged and become a corner and the contour is finished. The area of closed contours is indicated in blue.
Standard geometries are regularly shaped, closed contours with equally scaled hatches and equal angles of the corners.
Hollow bars can be created by moving a second, smaller closed contour inside the first closed contour. Only the outer area (outside the small contour and inside the large contour) is realized in the bar. The inner contour can have any shape, independent from the shape of the outer contour.