Not only is it a nice decoration, it also provides you with fresh herbs, flowers of vegetables.

Step 1: Materials

1- A knife
2- A pencil
3- Hydro pebbles (gravel will work to)
4- Glue (optional)
5- A plastic plant cup (they are free at a garden centre)
6- A small piece of foam (it must be water proof), you can buy it at a materesstore.

Step 2: Preparing the Cup

Cut holes in the cup.
If the holes are to big the hydro pebbles fall out.

Step 3: Cutting the Foam

Cut the foam in the shape of the cup. Also cut a hole in the centre of the foam, this will allow you to put the plant trough the foam.

Step 4: Put It All Together

Fill the cup with hydro pebbles, put the plant trough the foam and put it all together.
You can glue the foam to the cup but if you push it a little bit in the cup it will keep together.

Step 5: Let It Fload

Put the cup in the water and let it float.
In time the roots will grow and start coming trough the holes.
You can always paint it to make it look better. But be sure to use water proof paint.

After a time you can enjoy your fresh herbs and vegetables out of your own aquarium.