You'll need:
1) Conc nitric acid
2) Conc sulfuric acid
3) Cotton Wool
4) Sumlight
5) Fire source that makes you ignite the wool without hurting yourself
Method:
1) Place your cotton wool in a glassware, preferably wide mouth for convenience of taking it out later.
2) Pour in some nitric acid, just pour in enough amount to make it wet.
3) Pour in some sulfuric acid. A bit will do (few drops). Sulfuric acid will become the catalyst for the reaction between nitric acid and the cotton
4) Dry the cotton
5) Light up the cotton in an open space and far from anything and anybody.