If you just want a real showstopper of a fire, get hold of an old VW
engine block and burn it. Those are made of magnesium and boy, you better
wear welding goggles. Some good friends of mine got banned for life from
all Washington State campgrounds after they pulled this stunt at Alta Lake.
They still laugh when they tell the story, though.

Be careful crafting July 4th stunts. They can be life-threatening. Also,
defer doing this until after you have at least one child, that way you
won't qualify for the Darwin Awards when you kill yourself being stupid.

Grant