The ornamental design for a rotarybutton for a hand tool, as shown and described.
FIG. 1 is a perspective view of a rotary button for a hand tool 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 elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view of a embodiment of a rotary button for a hand tool showing my new design and the broken lines are for illustrative purpose and form no part of the claim.