When is flexibility for an interface needed and when is rigidness better? MetaSolid is an imaginary material that changes its state between soft and solid on demand. It allows us to explore the potential of future flexible interfaces that programmatically control their material characteristics. This video sketch proposes novel interactive and collaborative experiences around the idea of MetaSolid to stimulate future research and development on novel materials and interaction techniques. Besides classical gestures like folding or bending the interface, new ways appear, such as crumbling, stretching or tickling. These enable the user to easily form, display and modify virtual representations of real physical objects.