I have a fish bowl that I want to put some red cherry shrimp in, but I wanted some kind of filter for it, and a hob was out of the question. So I found a few different undergravel filters online, but I am too cheap to pay $15+ for one, plus shipping, so before I had to go to work today I dug out some stuff to try to make my own.
I have several of these thin plastic trays for my houseplants, so I decided to cut one to size, drill some holes all over in it and cut space for the plastic tube to fit in.
I put some small-ish stones I got from my garden in the bottom of the tank, placed the cut tray on top, put the tube in the hole I cut for it (and propped it on two o the stones so it wouldn't slide down to the bottom), covered it with gravel and put my plants back in. I then put in an airstone and started it. Once I got home I put my four immortal "feeder" guppies in it. So far they seem happy with their new setup... We shall see how well this works out.
"Things aren't always what they seem in this place, so you can't take anything for granted."