Millivolt power supply

Hello; I'm in need of a 0-50 mv source for testing some meters for my boss.All of the meters have iether curent or voltage scales but FS readings are all within the 0-50mv range. I thought of accordingly using a standard power supply along with a voltage divider but the resistor sizes

What type of meters? Moving coil meters are generaly rated in full scale curent, regardless of what the scale its self says unless the current limiting resistors are bulit in.

A variable power supply with a voltage divider

Presently one other accurate voltage source I forgotten about would be a Fluke differential voltmeter,like the 893 or similar ones. They measure voltage by bucking their internal contemptibly calibrated voltage supply against the input V,and occasionally nulling a sensitive meter.You could get one cheap on Ebay,or from a generally used
Test Equipment company.

Hook it up to your device under test(DUT),and adjust the Fluke for a full- scale reading on the DUT,and read the voltage out off the dials.

Keithley makes low voltage sources,try Ebay for some used ones,or look for meter calibrators.

IIRC,Keithley has a website,Google should find it.

Why not use the voltage divider on the input of an opamp setup as a unity gain noninverting buffer amp. The high input impedance of a noninverting amp would not load the divider,

Certainly you're almost always better off testing analog meters with current, cause which's what they measure.
If you need to know the voltage, measure it across the meter with a dvm.
Lots easier than tyring to build a softly calibrated voltage source. All you need is a sloppy voltage source