Integrating Java with PostgreSQL/PostGIS database offers a promising development platform for an object-oriented 3D building information system where an object-oriented 3D bulidng model can be proficiently constructed, analyzed and displayed while geometry data of the 3D bulidng model are efficiently managed. This research presents the prototype system integration design to methodically demonstrate how the system can be developed. This research also meticulously presents the logical and physical data models in designing the object-oriented 3D bulidng database. In addition, a reinforced concrete building was used as an implementation case study to validate the proposed prototype system as well as to demonstrate its potentials. Not only the proposed prototype system offers technological advantages, it is also an open-source solution that is free to acquire, customize and distribute. In order to fully exploit the proposed prototype system, multiple implementation issues are still required further research including how to overcome insurmountable data processing time when the model contains a large number of reinforcing steels and how to handle the complexity of mechanical and electrical systems{ geometry data. In addition, more functions to support building design and construction project management should be developed to better fulfill functional needs of construction companies as well as to add motives for the companies to use the system.