The ornamental design for a footbathbase, as shown and described.
FIG. 1 is a front upper perspective view of a footbath base showing my new design;
FIG. 2 is a rear upper perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a front view thereof;
FIG. 8 is a rear view thereof; and,
FIG. 9 is the perspective view as shown in FIG. 1 including a disclaimed broken line depiction of a footbath and chair.
The broken line showing of various regions in the figures, including the unshaded areas therein, is for illustrative purposes only and forms no part of the claimed design. The broken line showing of the footbath and chair in FIG. 9 is for illustrative purposes only and forms no part of the claimed design.