Rob Elliot and glass artist Jason Mack are set to return to once again build the World’s Tallest Glass Tree using recycled glass bottles donated by the community. Fridays 4-7 p.m., Saturdays, 12-7 p.m., Sundays, 3-5 p.m. Free to attend; must park in Williams Bay High School parking lot. Yerkes Observatory, Williams Bay; worldtallestglasstree.com.