How to make a Unicorn diffuser. You will require a plastic 2 pint milk bottle and a pair of sharp scissors (adult supervision may be required).
The bit you want is the bit under the label, so cut everything else off (trim for a nice finish). Cut along the line (formed from the two sides of the blow injection moulding mould) and hey presto you have two diffusers. They can be used solo or one on top of the other. If you find a small amount of printing on the plastic it should rub off using a green pan scrub.