A bubble baffle is a small, open toped plastic box that goes around the ruturn pipe on the skimmer. This box also has an open slot in the bottom. The filter material you are talking about, or similar material, is placed over the opening in the bottom of the box. The only way that water from your skimmer has to exit, is the hole with the filter over it. The bubbles, are "trapped" in the box, and most rise to the surface inside the box, without spilling into the aquarium. the rest are caught in the filter and are seperated, so the water coming from the skimmer has no bubbles when it leaves the baffle.
, you could just make a small acrylic box, a few inches by a few inches, that will fit around your return pipe. I would do it with 4 sides of acrylic, about 5 or 6 inches deep. Also, I would use a piece of acrylic to cover about half of the bottom opening. Then cover the opening with the filter (you can get more at the lfs
), and attach the box to the return line with plastic fasteners.
if you need more help, PM me and i will get with you with a diagram.