Abstract: A corner frame having a base for engaging the back of the foamboard and a top for engaging the front of the foamboard separated by sidewalls on the base which are of a width to permit positioning the corner of the foamboard within the corner frame thus covering and protecting the corners of the foamboard. The corner frame is an assembly of two pieces--a top and a base. The top and base, being separate, are connected to one another to form a corner frame by either a slide lock feature or a snap lock feature. The corner frame may be connected to the foamboard by spikes, other gripping means or a two sided adhesive. The corner frame also may receive a cord or wire so that the corner frames may be used to hang the foamboard like a picture and/or used to straighten warped foamboards or to prevent warping of foamboards.