Like the exterior of the building, the principal internal spaces are designed to make the best use of natural materials in their natural state. The structure and detail of the concourse galleries echo the form of the exterior, with the curving strata formed in native hardwoods. Oak, ash, beech, sycamore, alder, birch, chestnut and cherry woods from renewable sources in mid-Wales will be used together in proportions that reflect their relative availability from the forest. The design of the concourse galleries is intended to evoke the image of the edge of the forest, partly as a counterpoint to the coastal nature of the exterior, and partly because the edge of the forest in folklore and mythology represents a line between the real world and the magical world, a line which resembles the front edge of the theatre stage. The form of trees is created by the interweaving curvature of the gallery edges, and by the random positioning of the supporting columns. "—architect Jonathan Adams"