The ornamental design for a stringinstrumentbody, as shown and described.
FIG. 1 is a front perspective view of the string instrument body.
FIG. 2 is a front elevational view of the string instrument body.
FIG. 3 is a rear elevational view of the string instrument body.
FIG. 4 is a left side view of the string instrument body.
FIG. 5 is a right side view of the string instrument body.
FIG. 6 is a top view of the string instrument body; and,
FIG. 7 is a bottom view of the string instrument body.
The shading is provided to illustrate contour only and is not an indication of texture, gloss, etc. The broken lines illustrate the portions of the string instrument body that form no part of the claimed design.