I needed to make a filter for an upcoming snail tank.. it's a 6.5g mini-bow.
Here's what I did:
(The tube was an old container for api test strips)
I had no idea what I was doing... But it looks like its working, the bubbles are going up through the tube so I hope it'll work.
The biomedia is seeded from my main tank
The 'filter pads' is wrapped around the bottom and outside bottom of the tube, as I didn't have a sponge..
Holes are drilled on the bottom and sides at the very bottom
It's about 6 inches tall 3/4" or so diameter.
(took me 30 seconds in paint, I know it's crap :P )
and here's a pic: