Thermaltake Armor Top fan mod
I did this a while ago on my armor to improve airflow. The stock setup is horrible. The fan grill consists of a slab of plastic with small holes drilled in it as you can see here:
What I did was just take a dremmel around the outside of the holes and cut them all out! There is a nice honeycomb mesh underneath that serves as a grill. I also pulled out the stock 90mm fan and put in a 120mm.