There are many ways to implement programmable matter. One is to build it as a huge modular selfreconfigurable robot composed of a large set of spherical micro-robots, like in the Claytronics project. These micro-robots must be able to stick to each other and move around each other. However, the shape of these micro-robots has not been studied yet and remains a difficult problem as there are numerous constraints to respect. In this article, we propose a quasi-spherical structure for these micro-robots, which answers all the constraints for building programmable matter, helping the realization of an interactive computer-aided design (CAD) framework. We study different scenarios, validate the ability to move and propose methods for manufacturing these micro-robots.