I'm in the process of building a scale this week. I'm using a 4 wire load cell, connected to a INA125P amplifier, feeding an analog input on an atmel 328P. See "http://arduinotronics.blogspot.com/2013/04/this-weeks-projects-load-cells.html(Arduino Load Cell Scale)":http://arduinotronics.blogspot.com/2013/04/this-weeks-projects-load-cells.html