This isn't actually something you use to operate your aquarium, but it is a nice aquarium related decoration you can use on your fridge or anywhere else magnetic in your home. Perhaps a metal tank stand. I chose to do a clown fish magnet:
The magnet was created from Sculpey. This is an oven bake clay that is easy to mold.
First, you mold the Sculpey into your desired shape. I used a picture of a clown fish as guidance. Make sure the bottom is flat so that the magnets will attach evenly. I did my molding on a paper plate.
You can use a toothpick to add texture, as I did adding stripes on the fins. Also, you can add 3D elements, such as eyes or fins, by molding these separately and pressing them into the desired location on the base structure.
Then, bake the structure. I placed the fish on aluminum foil in the oven on 275 degrees F for 30 minutes. Follow the baking instructions on the Sculpey packet according to the thickness of your piece.
Once the structure is baked and has fully cooled, you may paint it. I waited a day before I painted it. I used water-based acrylic paint.
I waited 1 day after painting, and then I coated the fish structure with clear finger nail polish. This gives it a glossy, smooth appearance.
After the nail polish dried, I used a hot glue gun to attach two nickel-sized magnets onto the back. The magnets can be purchased at any craft store or Wal-Mart.
Allow the glue to fully set, and you've got yourself a fish magnet! (Or whatever shape you decide.)