This paper discusses a deployable-arch-structure design that is built using articulated bars, commonly called a scissor-system, and is based on the regular polygon geometry. The deployed-arch shape can be determined by inscribing regular polygon geometry in a circle. It is defined by the: a. number of bars required, b. position of the pivots, c. pivot-point distances, d. bar length, and e. open-geometry angle of the arches. The goal is a deployable half dome made up of semi-arches. Traditional arch construction depends on external structures to provide stability until the keystone is set, which then allows the supports to removed. Deployable structures avoid the need for these external supports greatly simplifying the assembly process and deployment time.