The ornamental design for a flathead for vibratingpaintbrush, as shown and described.
FIG. 1 is a top left rear perspective view of a flat head for vibrating paintbrush showing our new design with unclaimed environmental structure;
FIG. 2 is an enlarged top left front perspective view of the flat head for vibrating paintbrush showing our new design;
FIG. 3 is a top plan view of the head as shown in FIG. 2;
FIG. 4 is a bottom plan view of the head as shown in FIG. 2;
FIG. 5 is a left side elevational view of the head as shown in FIG. 2;
FIG. 6 is a right side elevational view of the head as shown in FIG. 2; and,
FIG. 7 is a front elevational view of the head as shown in FIG. 2.
The broken lines showing a handle in FIG. 1 are for illustrating the environment for the flat head for vibrating paintbrush and form no part of the claimed design. The shading lines shown in the drawings represent the three dimensional contour of the design and are not intended to indicate surface decoration.