FIG. 1 is a top, rear, and right perspective view of a three-line golf putter attachment according to the present design;
FIG. 2 is a top, front and left perspective view of a three-line golf putter attachment according to the present design;
FIG. 3 is a left side elevation view of a three-line golf putter attachment according to the present design;
FIG. 4 is a right side elevation view of a three-line golf putter attachment according to the present design;
FIG. 5 is a rear elevation view of a three-line golf putter attachment according to the present design;
FIG. 6 is a front elevation view of a three-line golf putter attachment according to the present design;
FIG. 7 is a top plan view of a three-line golf putter attachment according to the present design; and,
FIG. 8 is a bottom plan view of a three-line golf putter attachment according to the present design.
Broken lines are indicated in FIG. 1 for the purpose of illustrating a golf putter to which the three-line golf putter attachment is affixable, and form no part of the claimed design.