Final answer:
Manufacturing cylindrical fireworks shells is difficult due to the precision needed in shaping high explosives and ensuring the shell explodes symmetrically, resulting in the desired visual effects.
Step-by-step explanation:
Cylindrical fireworks shells may be more difficult to manufacture due to the precision required in their design to ensure they explode effectively. When dealing with high explosives, the manufacturing process must ensure that the explosive lenses are shaped correctly to direct the explosion efficiently.
This is similar to the precision needed in the implosion technique used for a spherical mass of plutonium surrounded by shaped charges in nuclear devices. Cylindrical shells must withstand the force of their rocket propulsion phase without deforming and must explode symmetrically to create the desired visual effect. Any asymmetry in manufacturing can result in non-uniform flight or explosion patterns, as evidenced by the differing trail densities in fireworks explosions that reflect the initial momentum of each fragment of the shell.