I found a beautiful mini lava rock at LPS
and thought it would look nice in my 100 gallon aquarium. When I got it home I realized that if I drilled a hole through the thickest side I could put a piece of air tube inside and maybe it would look better than a standard bubble stone. Wow, was I surprised on how good it looked and how well it functioned. I used no glue or silicon just a Dremmel and slow pressure and the air tube fit perfect. Although it is great for my tropical tank, I am afraid to make one for my 20 gallon goldfish tank because it has sharp edges and he bumps into things a lot!