The sling was a universal weapon throughout the history of Mesoamerican warfare.
The sling was typically wielded by commoner auxiliaries who launched stones or clay pellets into enemy formations en masse. The ammunition was either rounded stones or specially made clay pellets which were occasionally filled with obsidian flakes to maximize damage to soft tissue. In any case, the ammunition’s size was standardized in order to ensure that the user could maintain a consistent rate of fire and retain his accuracy.
The slings themselves were generally constructed of maguey fibers. It’s possible that the central strap which connects the two ropes was made of cut leather, but interlacing the fibers into a strap would have likely been just as effective as the image above shows.
The most effective means to utilize this weapon on a battlefield setting would have been to organize separate units of slingers, direct their fire, and coordinate a release of projectiles. How exactly their fire was directed and what signals they used to order a release are unknown and will likely remain that way.
The Spanish conquistador Bernal Diaz Del Castillo described sling-stones as some of the most troublesome projectiles that they faced during the conquest of Mexico. They were small, difficult to see, came in large numbers, and inflicted a great deal of damage to Spanish-Tlaxcalan formations. Although they may not be as lethal as concentrated arrow fire, sling-stones were undoubtedly important in Aztec battle strategy.