FIG. 1 is a top, front, and left side perspective view of a cap for a writing instrument showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a rear elevation view thereof with the cap and a writing instrument, shown in FIGS. 1-7, separated; and,
FIG. 9 is a bottom view thereof with the cap and writing instrument separated.
The broken lines showing the body of the writing instrument in FIGS. 1-5 and 7-9 and the inside of the cap in FIG. 9 are included for the purpose of illustrating portions that form no part of the claimed design.