Sensors & Sexy Design for Sports Equipment

Please, only engineers that have experience with sensors! We are developing sports equipment (already designed) and require an engineer with current knowledge dealing with sensors that will send an audible noise ("beep") when something crossing the range of the sensor. (1) The range of the sensor is only about 12-15 feet max (2) The sensor could be powered either by a small battery located in the equipment (3) Sensor would need an on/ off switch. (4) It would be best if the 12' sensor path was visible to the user of the equipment, like a laser beam, but the range would have to be limited to a specific length (12-15 feet). Maybe this could be done by requiring a small receptor to the "beam" (at the 12-15 foot point) in order for the beam to work? (We do not want the liability of having a laser go to an undetermined length. Also will require a the most creative / artistic designer to make our products look "sexy".