Custom rubber sealing?

[Sp4nk]

I just drilled a 90mm hole in my Antec Aria case and would like to wrap some kind of rubber trim or seal around the hole, but I'm not sure what kind of material to get. I've tried various hardware stores for gaskets or gromits with no success. Right now I've just got a basic screen behind the hole and by itself. Any ideas?

 

[Penguincomp]

Glass shop. They have stuff like that. Or a hobby store for round tubing that you could cut yourself and then glue into place. Those are your best shots. When I do custom windows, I just go to the local glass shop and buy the window rubber from them by the foot.