A homemade programable voltage calibrator
Your voltage divider idea only works if you have a voltage source of the requisite accuracy to be the power source for the divider. 0.1% resistors in a divider circuit do not magically make an accurate voltage if the supply to the divider has lots of noise and/or ripple on it or the absolute voltage level is not known to the desired accuracy level. 

Instead you should consider the use of an accurate shunt voltage reference. You can get these as accurate as you wish to pay for. They act as an almost perfect zener diode.