The ornamental design for a tubecap, as shown and described.
FIG. 1 is a side view of a tube cap showing our new design. No figures
depict the remaining sides, since these views of the design are identical
to the side view shown.
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof; and,
FIG. 4 is a bottom perspective view thereof, it being understood that the
interior sides of the bottom portion of the tube cap not shown are
identical to those shown.