A variety of different approaches have been employed to enable implantation of electronic medical microdevices. A novel method of producing low-cost, rapidly fabricated implantable enclosures from biocompatible silicone is presented in this paper. This method utilises 3D computer-aided design software to design and model the enclosures prior to fabrication. The enclosures are then fabricated through additive manufacturing from biocompatible silicone using a 3D bioprinter. In this paper, four different implantable enclosure designs are presented. A prototyping stage with three different prototypes is described, these prototype enclosures are then evaluated through submersion and operation tests. A final design is developed in response to the obtained results, and then evaluated in a long term temperature controlled submersion test. The evaluation results are presented and discussed. Several areas of future works are identified and discussed.