FIG. 1 is a perspective view of a portable workbench in an expanded position in accordance with the present design;

FIG. 2 is a front elevational view of the first embodiment of the portable workbench in an expanded position;

FIG. 3 is a right side elevational view of the first embodiment of the portable workbench in an expanded position, the left side elevational view being a mirror image thereof;

FIG. 4 is a rear elevational view of the first embodiment of the portable workbench in an expanded position;

FIG. 5 is a top plan view of the first embodiment of the portable workbench in an expanded position; and,

FIG. 6 is a right side elevational view of the first embodiment of the portable workbench in a collapsed position, the left side elevational view being a mirror image thereof.

It is to be understood that those portions of the portable workbench shown in broken line in the accompanying figures do not constitute an integral part of the claimed design and, therefore, are disclaimed as part of the claimed design.