Abstract: A guitar wall mount having wall hanging units that are movable and detachable includes a fixed base and the wall hanging units. The fixed base includes base rails. The base rails are horizontally assembled in sequence. The wall hanging units are detachably mounted on the base rails, and the wall hanging units are slidable along the base rails. One or more base rails are selected according to requirements. The guitar wall mount is mounted to a wall by tools such as screws, wall anchors, etc. The wall hanging units are able to be combined in various ways to meet placement and hanging requirements of stringed instruments, so the stringed instruments are hung neatly and beautifully. The wall hanging units are detachably mounted on the base rails, so the wall hanging units are able to be mounted independently or mounted together according to needs.

Abstract: A device includes a tube and a sleeve configured to at least partially encircle a portion the tube along its length. The tube is flexible and airtight and defines a longitudinal axis along a center of the tube, and is configured to bend along the longitudinal axis upon at least partial evacuation of the tube to form a joint. The joint defines a joint angle relative to the longitudinal axis, thereby approximating a revolute joint with torsional stiffness. Actuating a joint includes partially evacuating a flexible tube defining a longitudinal axis, thereby forming a bend in the tube at an angle with respect to the longitudinal axis at a perimeter of a rigid sleeve at least partially encircling the tube, and restoring a neutral pressure to the tube, thereby removing the bend in the tube.