The mouth plate is the rigid two-part structure inside a puppet’s head that the puppeteer’s hand opens and closes — the upper plate sits under the thumb-side palate, the lower under the fingers.
It is the one component where a small error is visible in every second of performance. Too big and the mouth flaps loose. Too small and the puppeteer’s hand cramps in ten minutes.
Sizing
The plate is fitted to the performer’s hand, not to the puppet. Trace your hand flat, fingers together, thumb separated, and build to that. Two builders working from the same pattern should still cut different plates.
Materials
Poster board or chipboard for a first build — free, cuttable with scissors, and stiff enough to learn on. Sintra or thin PVC board for anything that has to survive: rigid, lightweight, won’t soften with sweat, and can be heat-formed to a slight curve. Craft foam works as a soft-mouth alternative when a rounder shape matters more than a crisp one.
The hinge
The two plates join at the back with a flexible strip — fabric tape, a strip of fleece, or thin leather glued across the joint. What you are building is a hinge, not a fold. A creased plate cracks along the crease within a few dozen opens.
The gap
The most common beginner failure: the plates meet edge to edge, so the mouth never truly closes and the puppet looks permanently ajar. Build a slight overlap at the front so the lower plate tucks just inside the upper.
Line both plates in felt before assembly. Reaching in afterwards is a bad afternoon.