Surely the cheapest way to start calibrating multimeters would be to just buy a lab multimeter that you get calibrated which is an order more accurate than the calibration you provide to use as a reference? Buying a load of off the shelf sources etc is going to be a bit of a nightmare keeping them all in cal etc? with a precision meter you can setup your own sources, or automate by making a test fixture.
Surely the cheapest way to start calibrating multimeters would be to just buy a lab multimeter...
You can buy a calibrated lab multimeter for $50?
This thread is not about calibrating, it is about testing or verifying.