Complex sentence: Traditionally, the juice and stems were collected from the mountains and brought into town where copper vessels were filled with the raw mixture which was then beaten until it reached the desired consistency and fashioned by hand into the desired shape.
Split into simpler sentences: Traditionally, the juice and stems were collected from the mountains and brought into town where it was put into copper vessels. The raw mixture was then beaten until it reached the desired consistency and fashioned by hand into the desired shape.