Would this work?

http://www.ebay.com/itm/120mm-Fan-Silicone-Soft-Anti-Vibration-Noise-Reduction-Silencer-Gasket-Black-/151016314996?pt=US_Power_Cables_Connectors&hash=item2329461874
+
http://www.ebay.com/itm/COMPUTER-FAN-GRILL-FINGERGUARD-120mm-Black-/261298231558?pt=US_Computer_Fan_Grills_Filters&hash=item3cd6969906

Or what about these?
http://www.ebay.com/itm/120mm-Black-Aluminum-PC-Fan-Filter-Grill-Guard-for-Computer-Fans-/121178864953?pt=US_Computer_Fan_Grills_Filters&hash=item1c36d2bd39