PIPE CLEANER MAGNET BOTTLE
We cut pipe cleaners into small pieces and put them in a plastic bottle, then used a magnet to move them about inside the bottle.
MINI LAVA LAMP
We used a small plastic bottle to make a simple mini lava lamp. We filled the bottle three quarters full with vegetable oil and then filled the rest with a mixture of water and blue food colouring. This works best giving the bottle a good shake.
source: http://sunnydaytodaymama.blogspot.co.uk