You will need: salt (quite a bit!), pegs (or something to hold the feathers up), a few feathers you have found during your outdoor exercise (or you get buy some online for craft projects), water, as many glasses or containers as you have feathers.
To begin, you need to boil the water. Whilst the water is boiling, stir in (a lot!) of salt. You need to keep stirring it in, until it will not dissolve anymore. This makes a supersaturated solution.
Pour the water into the container and use a peg to clip the feather in a suspend it in a jar. Wait for 3 days, and keep checking in! You will see the crystals begin to form. It looks beautiful!