Abstract: A cornering tool is provided which may be used for application of drywall or plaster or similar construction coating materials. The tool is adjustable over a wide range of corner angles. In addition, the adjustability allows for use in plastering as well as drywall application where the angle is offset to effect screeding of excess coating material. The tool includes the novel feature in such tools of a thinned hinge section with increased flexibility which allows for angular adjustment of the blades without bending the blades out of plane. The tool is preferably formed of plastic.