FIG. 1 is a perspective view of a wall-mountable access panel assembly according to the present invention; FIG. 2 is a front elevational view thereof; FIG. 3 is a rear elevational view thereof; FIG. 4 is a top plan view thereof, the bottom plan view being a mirror image of the top plan view; and, FIG. 5 is a left side elevational view thereof, the right side elevational view being a mirror image for the left side elevational view.