The ornamental design for an electrictoothbrush handle, as shown and described.
FIG. 1 is a perspective view of an electric toothbrush handle, embodying the new design;
FIG. 2 is a right side elevational view of the electric toothbrush handle of FIG. 1;
FIG. 3 is a left side elevational view of the electric toothbrush handle of FIG. 1;
FIG. 4 is a bottom planar view of the electric toothbrush handle of FIG. 1;
FIG. 5 is a top planar view of the electric toothbrush handle of FIG. 1;
FIG. 6 is a front elevational view of the electric toothbrush handle of FIG. 1; and,
FIG. 7 is a rear elevational view of the electric toothbrush handle of FIG. 1.
The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design. Stipple shading represents a surface having a matt finish.