Three-dimensional cell agglomerates, such as organoids, are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1-mm) multicellular organoids using 100-MHz surface acoustic waves (SAW) without direct contact with the media or cells. Calcium ion signaling through these clusters suggests a continuous tissue construct: an organoid. They may be formed at will, and the method is feasibly useful for formation of numerous organoids in a single petri dish.