Creating Contoured and Plastic Parts - Autodesk Inventor 2010: No Experience Required - page 421

FIGURE 8.63 Building a pattern using an equation
FIGURE 8.64 Patterning the red lines using the same technique
All that's left is to create your grill.
Adding the Grill
With the Grill feature's many capabilities, all you really need is the boundary
and the ribs. Both your vertical and horizontal elements will be the same height
and depth:
1. Start the Grill feature from the Plastic Part panel.