Socks Studio has a short article and a bunch of photos of "The Toy."

“The Toy” was a self-assembly project made in 1951 by Charles and Ray Eames and sold by Sears, Roebuck and Co. This construction kit for children sums up the simplicity and playfulness of most of the Eames’ works. It comprised dowels with pierced ends, pipe cleaners and brightly colored panels (four square and four triangles) of plastic-coated resistant stiff paper. The pieces of “the Toy” came packed in a hexagonal tube and could be used to produce multiple structures, playhouses, theatres and shelters.

"The Toy" by Charles and Ray Eames (Via This Isn't Happiness)