This is how I made my skilter a very, very effective fitler/skimmer for my 10
gal nano reef.
You drill a small hle, then by twisting a pocket knife blade down in the hole, you slowly make the hole bigger, until it is the right size that you can thread the plastic piece that comes with the airstone through it...put a little silicone around it to make it leak proof.
If you want, you can put a 35mm film canister around the airstone, to help prevent bubble from leaving the chamber, but the filter media prevents all bubbles from returning to the main anyway.
I also use a hagen surface skimmer to skim the surface of the tank....my tank is totally protein free!
The pic is self explainitory.....the reaction chamber goes over top of the airstone, and wa-la!
Sorry for the quality!
FWIW......with this setup I have had an extremely effective filter and skimmer, and I would reccomend this setup to anyone with a nano tank. Cheap, easy, EFFECTIVE!