The ornamental design for stamp pad holder, as shown and described.
FIG. 1 is a front perspective view of a first embodiment of our design for the stamp pad holder;
FIG. 2 is a rear elevational view of the embodiment of FIG. 1;
FIG. 3 is a front elevational view of the embodiment of FIG. 1;
FIG. 4 is a top plan view of the embodiment of FIG. 1;
FIG. 5 is a left side view of the embodiment of FIG. 1 (the right side being a mirror image of the left side view);
FIG. 6 is a bottom plan view of the embodiment of FIG. 1;
FIG. 7 is a front perspective view of a second embodiment of our design for the stamp pad holder; and,
FIG. 8 is a left side view of the embodiment of FIG. 7 (the right side being a mirror image of the left side view).
The rear elevational view, front elevational view, top plan view, and bottom plan view of the second embodiment are the same as the corresponding views of the first embodiment, and are shown in FIGS. 2, 3, 4 and 6, respectively.