Widely adopted as a college textbook, “Stock Scenery Construction Handbook” is one of the easiest to use, and most complete manuals on scenery construction. It has over 200 full-page drawings showing construction techniques for every conceivable kind of stock scenery piece, from flats (plain ones, door units, hardwall, etc.), to platforms and step units (including two kinds of parallel platforms and even folding-brace stairs), to all kinds of soft goods like curtains and drops. The second edition added a chapter on paint.
Stock Scenery Construction Handbook