Abstract: A toy construction set includes a plurality of interconnecting toy construction pieces, the pieces being connectable to build a toy that reversibly transforms between a first toy form and a second toy form, the first toy form defining a longitudinal axis in a first plane and the second toy form defining a longitudinal axis in a second plane that has a surface normal that is different from a surface normal of the first plane; and a bidirectional transformation module. The bidirectional transformation module includes a body defining a first connector and a second connector, the first connector coupled to a first piece included in the plurality of interconnecting toy construction pieces, and the second connector coupled to a second piece included in the plurality of interconnecting toy construction pieces; and a flexible portion between the first and second connectors.