The ornamental design for an end frame for a futon, as shown and described.
FIG. 1 is a perspective view of an end frame for a futon illustrating the features of the invention relating to the end portion in solid lines, and in broken lines to show the environment in which the invention is claimed, with the broken lines not forming a part of the claimed design;
FIG. 2 is a frontal view of the end frame shown in FIG. 1, with the understanding that the back view is a mirror image of the frontal view;
FIG. 3 is an end view of the end frame shown in FIG. 2; and,
FIG. 4 is an end view of the end frame shown in FIG. 2, taken from the opposing end of the end view shown in FIG. 3.
It is submitted that the bottom view of the end frame does not form any part of the claimed design.