Nicely done.
Yes, very nice work on all of the project.
Thanks
What about calibration for the reference resistor error?
Yes, it does need to be calibrated, not sure what the non calibrated accuracy is. Calibration is a simple procedure as long as you have a know resistance that matches the range being calibrated.
As I don't have any resistance standards, or meters with equal resolution. I measured a reasonably low tempco, high wattage, wire wound resistor using a 5A current source and a volt meter and then used that as my reference.