The ornamental design for a tattoomachinepen, as shown and described.
FIG. 1 is a perspective view of the tattoo machine pen showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a left side view thereof; and,
FIG. 7 is a right side view thereof.
The broken lines shown in the figures are included for the purpose of illustrating portions of the tattoo machine pen and form no part of the claimed design.