Abstract: A device is disclosed for attaching a snap fastener having a first and a second snap fastener portion to a material. The device is adapted for use with pliers having a first and a second plier jaw. The invention comprises a first and a second support capable of mounting on the first and the second plier jaw. First and second threaded fasteners respectively secure the first and second supports to the first and second plier jaws. A first die insert includes a projection for locating the first snap fastener portion of the snap fastener relative to the first die insert. A second die insert including internal resilient means locates the second snap fastener portion of the snap fastener relative to the second die insert. First and second apertures are located in the first and second supports for respectively receiving the first and second die inserts.