The ornamental design for a switchbox, as shown and described herein.
FIG. 1 is a top perspective view of the claimed design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a front perspective view thereof;
FIG. 8 is a front perspective view, showing environment in broken lines; and,
FIG. 9 is a rear perspective view, showing environment in broken lines.
The broken lines shown in the drawings are included for the purpose of illustrating environmental structure and portions of the switch box that form no part of the claimed design.