This NX Tip video shows how to extrude with intersecting section curves in one feature. This is very useful to construct the complicated ribs for a molded part with single feature. First you have to create a "self-intersecting section" - where curves of the section intersect each other. Then select the curves. Use the Extrude command and give the desired height & select offset to two sided and you will see that the ribs are created. This has been shown in detail in the following video:
Siemens Nx tutorials for beginners & advanced users.