Portable printer

1. 1The ornamental design for a portable printer as shown and described.

FIG. 1 is a perspective view of a first embodiment of a portable printer showing our new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof;
FIG. 9 is an enlarged view of portion 9 shown in FIG. 1;
FIG. 10 is a perspective view of a second embodiment of the portable printer;
FIG. 11 is another perspective view thereof;
FIG. 12 is a front elevational view thereof;
FIG. 13 is a rear elevational view thereof;
FIG. 14 is a left side elevational view thereof;
FIG. 15 is a right side elevational view thereof;
FIG. 16 is a top plan view thereof;
FIG. 17 is a bottom plan view thereof;
FIG. 18 is an enlarged view of portion 18 shown in FIG. 10;
FIG. 19 is a perspective view of a third embodiment of the portable printer;
FIG. 20 is another perspective view thereof;
FIG. 21 is a front elevational view thereof;
FIG. 22 is a rear elevational view thereof;
FIG. 23 is a left side elevational view thereof;
FIG. 24 is a right side elevational view thereof;
FIG. 25 is a top plan view thereof; and,
FIG. 26 is a bottom plan view thereof.
The dash-dash broken lines in the drawings depict portions of the portable printer that form no part of the claimed design. The dot-dash broken lines in FIGS. 1, 10, 9 and 18 represent boundaries of the enlarged portions and form no part of the claimed design.