We present a new methodology based on ferromagnetic fluids in which the user can have direct interaction (input/output) through a tangible and malleable interface. Liquid Interfaces uses the physical qualities of ferromagnetic fluids in combination with capacitive, multi-touch technology, to produce a 3D, multi-touch interface where actuation, representation, and self-configuration occur through the malleable liquid, ferromagnetic fluid. This, combined with the ability to produce sound, enables users to create musical sculptures that can be morphed in real time by interacting directly with the ferromagnetic fluid.