of an archway. Straps can be used in place of keystones. They are long and wide (same as toggle) rectangles. They are easier to construct than keystones, but not as strong due to their narrower dimension and reduced glue/nailing surface area. A coffin lock or screws may be used to join securely adjacent flats, or traditionally with a lash line cleat, where cotton sash cord is lashed around cleats installed on the flat's edges. This allows for quick standing and striking of the set. Styles Broadway or stage flats are generally constructed of nominal ( actual) pine boards. The boards are laid out flat on the shop floor, squared, and joined with the keystones and corner blocks. The keystones and corner blocks are inset from the outside edge, which allows for flats to be hinged or butted together. They are then glued in place, and stapled or screwed down. The flat can then be flipped over and covered with muslin or decorative plywood. Toggles in a Broadway flat are placed on centers. Broadway flats can also be constructed using Half-lap and Cross-lap joints instead of keystones and corner blocks, and joins stiles, rails, and toggles, by sawing a deep half-lap at the ends of the pieces, and/or a deep dado groove mid-piece, which are then glued and stapled together. Dados can be made using a radial arm saw or table saw, and a dado stack cutter (two outer circular saw blades and one or more "chippers" between them, giving a much wider cut). Setting up for a dado stack is approximately the same as for preparing keystones and cornerblocks, but requires less layout, as the length of stiles, rails and, toggles are equal to the face of your flat. Hollywood or studio flats can be made in various thicknesses to suit a particular design, but are most often made of nominal ( actual) pine boards. The boards are laid out on edge on the shop floor, the ends are glued together and stapled or screwed. Keystones and corner blocks are not normally used. Once assembled, the flat can be covered with or decorative plywood, which is glued on and stapled. The toggles in a Hollywood flat are placed on centers. Hollywood flats may receive a muslin skin over the decorative plywood face. The face is covered in a mixture of water and white glue, the muslin is applied and the