A method and fastening device for attaching polyester fiber panels to a substrate, such as a wall or a ceiling. The fastening device comprises an anchor part for attachment to the substrate and a fastening part for attachment to the panel. The fastening part comprises a cylindrical portion, a helical member surrounding the cylindrical portion for penetrating the panel upon rotation of the helical member and a recess in the cylindrical portion for receiving the anchor part. The thread angle of the leading edge of the helical member is greater than the thread angle of the trailing edge.

A multi-piece locking fastener having an intermediate component exhibiting a plurality of interior threads arrayed in a first direction. A first fastener has a first enlarged head and a first stem exteriorly threaded in the first direction. A hollowed interior is formed in an end of the stem and exhibits a further plurality of interior threads extending in a second direction opposite the first direction. A second fastener has a second enlarged head and a second stem, upon which is configured a second exterior thread pattern extending in the second direction. The first fastener is installed through the intermediate component from a first direction, with the second fastener rotationally inter-engaging the exposed interior threads of the first fastener in the second direction until the second enlarged heads contact the intermediate component, with loosening of either of the first and second fasteners being prevented.