LiquiFab -- Building with liquids in weightlessness

Abstract: Existing digital manufacturing methods can be broadly divided into subtractive approaches, where material is removed from a bulk to reveal the desired form, and additive methods, in which material is introduced voxel-by-voxel to create an object. We here show a fundamentally different method for the fabrication of three-dimensional objects that is neither subtractive nor additive. Instead of removal or layer-by-layer material deposition, in LiquiFab we shape an entire volume of liquid polymer by subjecting it to a set of geometrical constraints under conditions of weightlessness. The physics of liquid interfaces then drives the polymer to naturally adopt a configuration that minimizes its surface energy. On Earth, we achieve weightlessness through neutral buoyancy, and show that a small, well-defined set of boundary surfaces can be used to drive the liquid into a desired form that is then solidified. By sequentially applying this process, complex architectures can be assembled from successive liquid-formed elements. Unlike additive manufacturing, where every point within the object must be individually visited by a print head or light field, LiquiFab forms the entire structure simultaneously. This makes the process highly scalable and opens the door to rapid manufacturing of large objects both on Earth and in space.