Sintra is a brand of expanded PVC sheet — a lightweight rigid plastic board that is the professional standard for puppet mouth plates.
Why builders use it
It is rigid enough to hold a mouth open and closed cleanly, light enough not to add fatigue, and completely unaffected by moisture. A cardboard plate softens with sweat over a long shoot; Sintra does not.
Thickness
Two to three millimetres suits most mouth plates. Thicker is unnecessarily stiff and heavy; thinner flexes under the hand and the mouth loses definition.
Cutting
Score deeply with a craft knife against a straight edge and snap along the line, or cut with a fine-tooth saw or rotary tool. It cuts cleanly and does not fray or delaminate.
Heat forming is the real advantage
Warmed with a heat gun, Sintra becomes pliable and holds whatever curve it cools into. A gently domed palateThe palate is the roof of a puppet's mouth — the upper hal... is far more comfortable under the fingers and looks more organic than a flat plane. Work slowly and keep the gun moving — it scorches and the scorch is permanent.
Gluing
Contact cementContact cement is a flexible solvent-based adhesive applied ... bonds it to foamFoam is the structural material most soft puppets are built ... More and fabricFabric is the outer surface of a puppet — the skin, the cl... More well. Rough the surface lightly with sandpaperSandpaper and sanding sponges are used in puppet building to... More first; the factory finish is slick and the bond is noticeably better on an abraded surface.
The beginner path
Build your first plates from poster board or chipboard, which cost nothing and cut with scissorsScissors and shears are the primary cutting tools in puppet ... More. Move to Sintra once you know the shape you want and are building something meant to last.
Sourcing
Sign-making and plastics suppliers rather than craft shops. Offcuts are often cheap and a mouth plateThe mouth plate is the rigid two-part structure inside a pup... More needs very little material.
The hack: template in card, test it in your hand, then cut the Sintra once. Every hour spent on the cardboard version saves material and frustration.