Platforms, stairs, and similar objects are what are usually referred to as three-dimensional scenery.
Multilevel stage floors make it easy for directors to create interesting blocking pictures. To create these levels they use platforms. There are several types of platforms and a number of techniques for joining them.
Possibly the easiest stage platform to build is the rigid wooden platform. It is also the least expensive. This type has the added bonus of having detachable legs which makes the height easily varied. The framing for a rigid platform is usually made of 2 X 4 but 1 X 6 or 2 X 6 is sometimes used. The frame is a construction like a ladder, with joists (rungs) that are spaced no more than two feet apart. Although this type of platform can be made in almost any irregular shape most theatre’s stock inventory are usually eight feet long by four feet wide.
A second type of platform is a rigid steel-tubing platform. The framework is made from sixteen-gauge 1 X 2 steel tubing, and the top from three-quarter-inch plywood. Steel plates one-quarter inch thick called gussets are welded to the frame. Gussets are designed to accept casters or legs. These are predrilled in a pattern that matches the hole pattern on a caster flange or shop-built leg base. So the platform can be locked to an adjacent unit casket locks are attached to the underside of the platform in a uniform pattern.
A variety of materials can be used to make legs for rigid platforms. Whether they are wooden or metal, legs over eighteen inches tall should be braced. This is because the sideway forces exerted on the platform by the movement of the actors can easily break either the joint between the leg and the platform or the leg itself. To take advantage of the structural strength of the triangular form, braces should be placed so that they form a triangle between the leg and the rail.
Another type of platform is a stressed-skin platform. Stressed-skin construction consists of applying glue and securely screwing down the skins made of plywood to the internal skeletal framework. This form of construction is preferred. The skin and the frame are securely interlocked, which evenly distributes the load throughout the entire construction, instead of just to the joists. The skins may be laminated from two separate sheets of 1/4 inch plywood, which, may be used to make surfaces with a curve in them. Using this method of construction, any platforms that may be longer than 8 feet, will only need support applet at the ends of the platform. The strength in this type of construction is dependant on the secureness of the interlocking components. This makes it essential that all the edges of the plywood skins are properly attached and supported by the internal framework.
Honeycomb-Paper Lamination is another lamination method. It is based on the same principles used to make the extremely strong and lightweight wings of super-sonic aircraft. A continuous glue bond between the honeycomb and its covering skin is what the strength of this type of lamination depends upon. These platforms are made by sandwiching honeycomb paper between two sheets of plywood.
The parallel is another type of platforming that comes in two varieties. These are contenintal and standard. The top is removable in both types. The framework folds for compact storage. The height of the framework is not variable though. The folding patterns of the two types are different. The center support of the continental parallel is removable. Parallels can be built in almost any size but they are usually four feet by eight feet.
There are two types of stairs used in scenic construction. These are dependent stairs and independent stairs. Dependent units need support from some other element. This is usually a platform. Independent units are self-supporting. The actual units are built almost the same way, the only difference being what supports them.
Another type of three-dimensional scenery is wagons. Wagons can be made from parallels but are usually rigid platforms that lay on casters instead of legs. Skids are low-profile, casterless substitutes for wagons.
Resolves, which are sometimes called turntables, are large circular platforms that pivot on their central axis.
Other three dimensional scenery such as irregular platforms, rocks, and three-dimensional trees are all built similarly. The basic principles of platform building are followed when building stage rocks and other irregular platforms. Although the scenic designer ultimately decides the actual shape of these units, the only significant construction difference is that surfaces of rocks and irregular platforms are not straight, square, and level.
Source:
Limited experience in a scene shop
Gillette, J. Michael. Theatrical Design and Production. 4th ed. Mountain View: Mayfield, 1999