The ornamental design for a kettlebase, as shown and described.
FIG. 1 is a perspective view of a kettle base, showing my new design;
FIG. 2 shows a right side view of the kettle base of FIG. 1;
FIG. 3 shows a left side view of the kettle base of FIG. 1;
FIG. 4 shows a rear view of the kettle base of FIG. 1;
FIG. 5 shows a front view of the kettle base of FIG. 1;
FIG. 6 shows a top view of the kettle base of FIG. 1; and,
FIG. 7 shows a bottom view of the kettle base of FIG. 1.
The broken lines showing portions of the kettle base are for the purpose of illustrating environmental structure and form no part of the claimed design.