An apparatus and associated method for constructing prefabricated foam panels is provided. While making a longitudinal pass over a foam block, the apparatus flattens the foam block, cuts longitudinal kerfs in the foam block, and draws metal studs into the kerfs. The apparatus comprises a unique, heated blade having a shape similar to the cross section of a metal stud. The blade kerfs foam blocks, including blocks made of recycled or low-grade foam. The associated method includes kerfing the foam blocks by passing the blade through the foam blocks and drawing metal studs into the kerfs.