you can make a microohm meter with a 5$ digital scale, kelvin clips and two resistors and an adjustable resistor.
its pretty easy: the digital scale takes the one part per thousand change in resistance of the strain gauge at full scale (which works out to about 2.4 millivolts full scale (when run from two nicad batteries)) and amplifies it about 500? times and sends it into the adc
basically cut the wires going to the strain gauge and run all 4 wires to the kelvin clips, red to one clip black to the other, but you add two resistors (68 ohms is a good start) each in series with the red and blackwires, add the variable resistor in for callibration.
the polarity of the white and green wires doesn't matter, run them to the kelvin clips.
how it works is pretty simple: when you clip the kelvin clips on something, tare the meter. the two 68 ohm resistors limit the current flowing through the clips to about 17 milliamps. when you move the clips to the resistance you are intending to measure, the white and green wires now have say, 17 microvolts across the unknown resistor if you measured a .001ohm resistor. 17 microvolts will correspond to about 10 grams on a 1KG scale with two 68 ohm resistors iirc.
because the battery is supplying the voltage, pushing current through the resistors and the kelvin clips.. and because the battery is also the reference for the ADC, battery voltage does not matter. the digital scale is basically making a resistance comparison between the resistance in series with the test resistance. as long as you have low temperature coefficient resistors, the accuracy of this measurement is pretty good, about accurate to 1 part in 1000.
anyhow i need to get off my ass and make some of these meters, let me know if anyone wants one.