I doubt you will want to make your own exploding billiard balls, but you might want to try nitrocellulose as a model rocket propellant, as flash paper, or as a lacquer base. Nitrocellulose is extremely easy to make, but be sure to read through the instructions carefully before proceeding. As far as safety goes: Any protocol which involves strong acids should be performed by qualified persons wearing proper safety gear. Nitrocellulose cannot be stored for long periods of time, as it gradually decomposes into a flammable powder or goo (which is why many old films have not survived to the present day). Nitrocellulose has a low autoignition temperature, so keep it away from heat or flame (until you are ready to activate it). It does not require oxygen to burn, so once it ignites you cannot put out the fire with water. With all that in mind:
Christian Friedrich Schönbein's procedure has been widely used. It calls for 1 part cotton to 15 parts acid.
- concentrated nitric acid
- concentrated sulfuric acid
- cotton balls (almost pure cellulose)
- Chill the acids below 0°C.
- In a fume hood, mix equal parts nitric and sulfuric acid in a beaker.
- Drop cotton balls into the acid. You can tamp them down using a glass stirring rod. Don't use metal.
- Allow the nitration reaction to proceed for about 15 minutes (Schönbein's time was 2 minutes), then run cold tap water into the beaker to dilute the acid. Allow the water to run for a while.
- Turn off the water and add a bit of sodium bicarbonate (baking soda) to the beaker. The sodium bicarbonate will bubble as it neutralizes the acid.
- Using a glass rod or gloved finger, swirl around the cotton and add more sodium bicarbonate. You can rinse with more water. Continue adding sodium bicarbonate and washing the nitrated cotton until bubbling is no longer observed. Careful removal of the acid will greatly enhance the stability of the nitrocellulose.
- Rinse the nitrated cellulose and allow it to dry in a cool location.