A set of preforms to make a container for beverages, comprising an external preform and an internal preform, each intended to form respectively an external keg and an internal bag of the container. The internal preform is associated internally with the external preform in order to define with the external preform a hollow space. The external preform and the internal preform have respective coupling members suitable to clamp the external preform and the internal preform with respect to each other in a desired reciprocal position.