Humanoids remain luxurious robots, not easily purchasable or reproducible. The Robota project aims at building a low cost open humanoid platform, for use as educational tool for normal and disabled children. This paper reports on the mechanical design of a miniature 7 degrees of freedom articulated arm and of a miniature 3 degrees of freedom pair of eyes for Robota. We describe in details the mechanical construction, the electronic circuits and the control system, so that these could be easily duplicated by other laboratories.