The ornamental design for a combined mount accessorybase and support for variable-size phone grips, as shown and described.
FIG. 1 is a bottom perspective view of the combined mount accessory base and supports for variable-size phone grips according to the present invention;
FIG. 2 is another bottom perspective view thereof;
FIG. 3 is a top perspective view thereof;
FIG. 4 is another top perspective view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a right side view thereof;
FIG. 8 is a left side view thereof;
FIG. 9 is a front view thereof; and,
FIG. 10 is a rear view thereof.
The broken lines are included for the purpose of illustrating environment and form no part of the claimed design.