“Exercise was to be derived automatically in running up and down the curved surfaces,” Isamu Noguchi said of his design for the Contoured Playground, which was to be made entirely of “earth modulations.” The playground was never realized, alas, but The Noguchi Museum is featuring a 10-foot-square enlargement of its sculpted landscape, biomorphically curving, as the centerpiece of a new exhibition. Also on view are various iterations of the mold Noguchi first cast in 1941. —J.V.