The ornamental design for a spool for filament of a three-dimensional printer, as shown and described.
FIG. 1 is a top, front perspective view of a design for a spool for filament of a three-dimensional printer;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines that are immediately adjacent to the shaded areas and define unshaded regions depict the bounds of the claimed design, while all other broken lines are directed to environment. The broken lines form no part of the claimed design. The attached Appendix includes additional images and drawings of the spool for filament of three-dimensional printer.