OMG this picture collage has the coolest concept. I love how this image is all black and white and then there is a colour splash on the water in the hula hoop. They have done a very good job editing this image.
Use parchment paper and painters tape to get the layout just right BEFORE drilling holes in the walls. I have seen this before but they traced the frames and put up a whole sheet with the outlines and hangers rather than individual cut outs