The ornamental design for a monitorcase, as shown and described.
FIG. 1 is a right perspective view of the monitor case showing the new design in a first state in which the lid of the monitor case is open, such that the monitor and inner design features of the base can be seen;
FIG. 2 is a left perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a front elevation view thereof; and,
FIG. 5 is a right perspective view of the monitor case in a second state in which the lid of the monitor case is closed.
The broken lines and unshaded surfaces bounded by broken lines form no part of the claimed design.