Concrete is a fluid that offers the opportunity to economically create structures of almost any geometry - concrete can be poured into a mould of almost any shape. This fluidity is seldom used, with concrete instead being poured into rigid moulds to create high material use structures with large carbon footprints. The ubiquitous use of orthogonal moulds as concrete formwork has resulted in a well-established vocabulary of prismatic forms for concrete structures, yet such rigid formwork systems must resist considerable pressures and consume significant amounts of material. Moreover, the resulting member requires more material and has a greater self-weight than one cast with a variable cross section.