The main species is Castilla elastica, one of several plants from which rubber has been extracted.

Most balls were made from latex sap of the lowland Castilla elastica tree.

In pre-Columbian times, the guayule was a secondary source of latex for rubber, the principal source being the Castilla elastica tree.

Ancient Mesoamerican civilizations used the morning glory species Ipomoea alba to convert the latex from the Castilla elastica tree and also the guayule plant to produce bouncing rubber balls.

The figurines were made of sap from the Castilla elastica tree, which was seen as blood from the tree and is thought to represent the blood sacrifices in some of the Lacandon ceremonies.

The latex gathered from Castilla elastica was converted into usable rubber by mixing the latex with the juice of the morning glory species Ipomoea alba which, conveniently, is typically found in the wild as a vine climbing Castilla elastica.