Beth created the construction toy Ply as a way to build familiar and unfamiliar forms using natural materials. Beth chose black and white ebony wood for its irregular and beautiful striations, inherently making each construction piece unique. She wanted the forms to be simple in isolation but build to more complicated patterns, similar to the modus operandi of nature. She wanted to complement the simple toy with a simple bag, made of leather. Its handle and closure were designed as one in order to avoid hardware that could hurt children in transit and also provide a quick and reliable solution for opening and closing that would encourage clean up.
The name of the toy was inspired by the versatile nature of the toy: the word Ply represents play, poly, and ply[wood].