The ornamental design for a design accessory, as shown and described.
FIG. 1 is a perspective view of the design accessory, showing my new design in a first environment;
FIG. 2 is a front view of the design accessory shown in FIG. 1;
FIG. 3 is a rear plan view of a design accessory as shown in FIG. 1;
FIG. 4 is a left-side elevational view of a design accessory as shown in FIG. 1;
FIG. 5 is a right-side elevational view of a design accessory as shown in FIG. 1;
FIG. 6 is a top plan view of a design accessory as shown in FIG. 1;
FIG. 7 is a bottom plan view of a design accessory as shown in FIG. 1;
FIG. 8 is a perspective view of the design accessory as shown in FIG. 1 in a second environment; and,
FIG. 9 is a perspective view of the design accessory as shown in FIG. 1 in a third environment.
The broken line showing a portion of a design accessory, and each of the environments, is for illustrative purposes only and forms no part of the claimed design.