In this paper, we describe a prototype of a space filling display, Cloud Display. These days we have seen many different kinds of 3D displays. However, most of them are based on a conventional flat display with parallax imaging techniques, which means we still have such a constraint as to see images only nearby a display. In our laboratory, we have proposed to make a space itself become display by filling the space with controllable passive or active light scattering particles such as water drops, LED, and leaves. In this paper, we propose a space filling display based on smoke rings and show some results from our 4×4 arrayed smoke ring generator prototype system.