A native of Florida, Manus studied first at Rollins College in Winter Park before enrolling in the Art Institute of Boston, which she graduated in 1973. It was there that she threw herself into sculpture. Under the tutelage of her professor Michael Phillips, she explored a variety of media, including cardboard, wood, and steel. Her early works were rough and raw, bolted together and exploiting the rusting surface of steel. She turned to welding when the bolted wood started to warp and distort. She credits Phillips with teaching her how to weld, the process that has been her working mode ever since.
Already in her student years Manus was fascinated with the works of the Russian Constructivists. A stint in New York City introduced her to other artists who shared this interest, among them Joel Shapiro and Mark di Suvero. They both were experimenting with geometric forms and exploring the ways that abstract geometric structures could project a sense of movement and balance and alter the space around them. These were issues that were also preoccupying Manus as she shaped corten steel plates into sculptures that already exhibited her ability to create paradoxical structures that changed from every perspective.