The ornamental design for a shaft for a markinginstrument, as shown and described.
FIG. 1 is a top plan view of a shaft for a marking instrument showing my
new design;
FIG. 2 is an enlarged scale left end elevational view;
FIG. 3 is an enlarged scale cross-sectional view thereof taken along line
3--3 of FIG. 1; and
FIG. 4 is a modified form of the shaft for a marking instrument.
The left end view of the modified embodiment at FIG. 4 is essentially the
same as FIG. 2 but with the shading indicating the direction of the twist
being reversed.