Abstract: A method is disclosed of securing filaments to a toothbrush handle that is foldable along a longitudinal axis to acquire a functional configuration, the method includes providing a mold device for the toothbrush handle, the mold device comprising an upper member and a lower member positionable to define a mold cavity therebetween and a corresponding parting line therebetween, positioning filaments partially within the mold cavity, the filaments arranged linearly within the mold cavity in a plane that is parallel to the parting line, injecting a flowable plastic material into the mold cavity, and allowing the plastic material to cool and at least partially solidify within the mold cavity.