How to get 3ds xl speaker filters?

When I was taking my 3ds xl apart a while ago to fix the lcd top screen, as i was taking out the speakers, one of the rectangle speaker filter frame things fell out, and i was never able to find it. I have the other one, as well as the other black speaker fiber rectangle things. It seems the things that go under each of the speakers is that frame and the fiber things. I already replaced the screen, but i didnt want to put it back together without adding the other speaker filter yet.

So where would i get another speaker filter frame?