The ornamental design for a keyboardstand, as shown and described.
FIG. 1 is a perspective view of a keyboard stand showing the new design;
FIG. 2 is a perspective view thereof;
FIG. 3 is a bottom view of the keyboard stand of FIG. 1.
FIG. 4 is a top view of the keyboard stand of FIG. 1.
FIG. 5 is a front elevation view of the keyboard stand of FIG. 1.
FIG. 6 is a rear elevation view of the keyboard stand of FIG. 1; and,
FIG. 7 is a side elevation view thereof.
The broken lines showing a keyboard and wrist support in FIGS. 1, 2, and 7 are for the purposes of illustrating the environment of the article only and form no part of the claimed design.