Magnesium powder is used in a wide variety of compositions, both for spark effects and 'normal' fuel purposes. Relatively coarse magnesium is used for spark effects. In flares and some bright colored star compositions it functions as a normal fuel. It is superior to aluminum in color compositions since MgCl2 and MgO are more easily vaporised than the corresponding aluminum compounds. This reduces the amount of black-body radiation and improves the color purity.
Magnesium powder is available from dedicated pyro suppliers. Making magnesium at home is very difficult. Magnesium can be bought in boating supply stores. It is used to prevent corrosion of a ships hull. For that purpose it is welded to the hull. The lower position of magnesium in the electrochemical series will make the magnesium corrode before the steel will. Making such a block of magnesium into a fine powder will not be easy. Filing or cutting and ball milling may be tried. Ball milling of metals can be dangerous however since the metal can become pyrophoric. However, if a person is to drill a lot of holes and collect the shavings, these may be ball milled quite easily.
Magnesium dust is harmful and a dust mask should be worn when handling fine dust. Mixtures containing nitrates, chlorates or perchlorates and magnesium sometimes heat up and may ignite spontaneously, especially when moist. Coating magnesium with linseed oil will prevent reaction with most oxidizers, but this treatment does not protect the magnesium from ammonium perchlorate. Only treating the magnesium with potassium dichromate will prevent this reaction. This is done by boiling the magnesium in a 5% potassium dichromate solution. The magnesium will turn brown when this is done. Adding fine potassium dichromate powder to such compositions may also help.