The playpen is made of wood and acrylic slats. Wood is chosen to give a sense of nature, which is inspired by research showing that natural scenes (and materials) promote a sense of tranquility and well-being.  The acrylic slats, whose transparent properties allow unobstructed viewing into and out of the restricted area, are chosen to promote spaciousness, which is also tied to well-being. Note that about 90% of light is transmitted through acrylic, while the other 10% is reflected in a mirror-like fashion.  This reflective property produces visual motion along the slats as children and caregivers move around the daycare space.  Not only is this reflective motion interesting from a design perspective, the moving aspect is interesting from a developmental perspective as research has shown that young infants prefer moving vs. stationary stimuli.