FIG. 1 is an isometric view of the collapsible support device in a first position.

FIG. 2 is a top plan view thereof in the first position, and a bottom plan view thereof is identical to the top plan view.

FIG. 3 is a left side view thereof in the first position, and a right side view thereof is identical to the left side view.

FIG. 4 is a front view thereof in the first position, and a rear view thereof is identical to the front view.

FIG. 5 is an isometric view of the collapsible support device in a second position.

FIG. 6 is a bottom plan view thereof in the second position.

FIG. 7 is a top plan view thereof in the second position.

FIG. 8 is a left side view thereof in the second position.

FIG. 9 is a right side view thereof in the second position.

FIG. 10 is a front view thereof in the second position.

FIG. 11 is a rear view thereof in the second position.

FIG. 12 is an isometric view of the collapsible support device in a third position.

FIG. 13 is a left side view thereof in the third position.

FIG. 14 is a bottom plan view thereof in the third position.

FIG. 15 is a rear view thereof in the third position.

FIG. 16 is a right side view thereof in the third position.

FIG. 17 is a top plan view thereof in the third position; and,

FIG. 18 is a front view thereof in the third position.

The portions of the collapsible support device shown in broken lines form no part of the claimed design.