Use a poster board, any kind of squared wood for bottom with edges & Christmas lights; cut any size holes in posterboard; Christmas lights sit on bottom of square; shape the poster board & use a thin line of hot glue to hold them together = nightlight.
Hope to someday have a house with room for this type of mudroom . I am loving this mudroom. Looks like I found the answer to my laundry room dilemma. I plan to put my washer/dryer on the wall opposite this set up. I already have the beadboard walls.