In high school I experimented with making my own model rockets. Using books and online guides, I learned to combine potassium nitrate and different forms of sugar together to create solid rocket fuel. Potassium nitrate can also be used to create black powder and smoke bombs. As such, it was very difficult to find in Canada, but after months of searching I finally found it in a hydroponics store. At first, I made simple rockets which consisted of nothing more than a 2 inch rocket motor attached to a balancing stick. These rockets could fly up to about 100m. Later, I experimented with the design, trying to add fins for more stable flight and a parachute recovery system. I made a small amount of my own black powder, which I used to make fuses to light the rocket, and as a charge in the rocket to eject its parachute after the rocket motor was spent.
In the process, I designed and built my own ball mill. A ball mill uses a rotating drum filled with balls to grind very fine powders required for efficient rocket motors. I used an old furnace fan motor we had lying around to power the mill. The drum was made of PVC pipe, and filled with lead fishing sinkers so that it wouldn't spark.