Active Implantable Medical Devices (AIMDs) are essentially complex electronic systems which has to be surgically introduced inside the human body for diagnostic or therapeutic purposes. To ensure a good coexistence between the implant and the biological organism, a key role is played by the package. This thesis project deals with the design of a 3D printed polymeric package for medical electronic implants. The package is in direct contact with the living body environment and, to this purpose, first of all, it must be hermetic and biocompatible. Since any living body implant site constitutes a wet environment, it is fundamental to guarantee a good moisture barrier to save the electronics inside the cavity and to ensure safety for the patient.