Amate is made from the bark of a spectacular Ficus tree. I saw this one in the Cacahuamilpa park. They used to be regionally abundant but have been over used and are environmentally sensitive.
Making Amate paper involves the use of stone beaters. Ernesto found these ones near his house in Tepotzlan, the town was once a center for paper production. The beaters are about the size of a bar of soap. The working surfaces of these are quite glazed from use. Since Amate paper dates back at least to 75CE these could be quite old!