The ornamental design for a hand-operated embossing machine, as shown and described.
FIG. 1 is a perspective view showing the front, right side and top of a hand operated embossing machine which forms our new design, the small spaced rectangles shown in this and other figures are understood to simulate stitching, and the medallion shown in broken lines in this and other figures being for illustrative purposes only and forming no part of our design;
FIG. 2 is a perspective view showing the rear, left side and top thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof; and,