Design in a Building Information Modelling (BIM) environment, in a sense, is similar to playing Lego; a designer puts various objects together to form his/her design. The availability of BIM objects, or say the Lego pieces, is one of the most critical issues for promoting BIM implementation. Existing BIM objects, however, are far from comprehensive. Neither is there a Oone-size-fits-for-allO objects library; one has to develop a localised library suiting a particular construction setting. The efforts to tailor-make such a library incur huge costs, which partly explains the mundane BIM implementation in many economies. This paper explores an effective approach to develop an open access BIM objects library focusing on Hong Kong. It does so by (a) determining an ontology-based structure of the library; (b) defining the BIM objects parameters; (c) developing an object processing module (OPM) to unify and integrate the objects from other sources; and (d) exploring the sustainable development of the library. Although further studies are desired to bring it into full reality, the BIM objects library is expected to facilitate building design and information management in a BIM environment. It will also promote BIM implementation in Hong Kong and serve as useful references for other economies.