A magnetic fishing pond. Simply, cut out a pond from a piece of blue card or craft foam. Various fish shapes from thick coloured paper. Attach a paper clip to each fish. Build two fishing rods by adding some string to a pencil. The “hook” is made from two pieces of self adhesive magnetic tape (This link is just an example, browse and get it as cheap as you can). Sandwich the string between the bits of tape and there you go, time to cast off.