-- Shirley Lauro
The simplest way to bind a script is with standard "Term Paper Covers." These are made of soft cardboard or plastic and have built-in brads. They're sold in nearly every stationary store. If you use the kind with a clear plastic top cover, you don't need a label since your Title Page will show through. If you prefer the sold kind, you'll need a label centered in the upper half of the top cover with the Title and your name typed on it as on your Title page.
Don't use 3-ring binders or hard covers. They're more expensive, tough on readers, and don't stack well. And don't spend the money on any kind of permanent binding, spiral or otherwise. Once you get into readings and workshops or productions, you'll be rewriting and replacing pages at an alarming rate. And you can't do that if the manuscript's welded together.
Be kind to Literary Managers and the Judges of play Competitions: whatever kind of cover you use, make sure it's designed to enclose any sharp parts of the metal binder [brads, Acco fasteners]. Most playwrights practice this humanitarian act. It's fine if your play makes these folks bleed in their souls, but anything other than metaphorical blood won't earn you any points.
http://www.vcu.edu/arts/playwriting/