I claim the ornamental design for a tool holder, as shown and described.
FIG. 1 is a right, front perspective view of a tool holder showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a right, rear perspective view thereof; and,
FIG. 9 is a right front perspective view of the tool holder, holding a plurality of tools.
The features shown in broken lines depict environmental structure. The broken lines immediately adjacent to the shaded area represent the boundaries of the claimed design. None of the broken lines form part of the claimed design.