The best place to find these is at a local computer shop. They tend to pile up. One issue you will find is that not all "blanks" will fit in all "holes". Case makers tend to make varying designs for their particular cases. You may have to grab several to find one that fits. Some cases (Cooler Master comes to mind) have the very mesh type blanks/covers you are looking for. Computer shop, my friend, that is your place. Good luck!