Object-oriented programming and concurrency are increasingly popular in computing education. Both are difficult topics in themselves, and the combination of both introduces subtle interactions that are not easily understood. We propose the development of a visualisation tool to illustrate both object-orientation as well as concurrency issues. Designing such a tool is a challenging task. It has been shown that visualisation tools are not always as effective as their authors had hoped, and the issues to be illustrated by our potential tools are not yet well defined. In this paper, we investigate both the visualisation aspect and the functionality that such a tool may have and we develop some guidelines for the design of a concurrent object visualisation tool.