I pulled all the old nails out and took off the old screen, then sanded and painted the door grey -- Walmart Colorplace Grand Smoky Mountain. I then sanded lightly and rubbed on a walnut water-based stain to really make it look like the old wood. Dark wax would also work.
I then cut square chicken wire to cover the back instead of using screen. I stapled that on the back of the entire door.
I covered about 2/3 down with burlap, also stapled on, and left the bottom uncovered as the air intake for the heat pump is in that room, plus I didn't want it to be too monochromatic. I covered the staples on the back of the door with a 1" wide strip of thin trim wood, also stapled.
We hung the door with hinges where the old door was taken out, and I attached an old handle.