A voice operated calling card system and method. The channel is sized and shaped to substantially enclose existing fasteners on the structure to substantially prevent lateral movement of the bracket along the existing building panels. The handle of the trowel is rotated both to adjust the speed of rotation of the trowel blades and the cant of the trowel blades. The target device can obtain information of relative positioning of the target device and the mobile device determined for the purposes of providing an optical link between the target device and the mobile device and the optical component thereof can be aligned with the optical component of the mobile device based on the information. Transponders can be positioned in physical proximity to graphics or alphanumeric characters and this proximity can be stored in memory such that a user altering a specific transponder represents specific data to a controlled system or memory. The invention also relates to a centrifuge bowl for accommodating a rotor device having microchannel structure, and a method for producing the rotor device and the centrifuge bowl.