sshneider
This would me 2 valves and some kind of a mixing/impingement  chamber.  Does the dispense valve device you showed us do this?
Personally, I don't see how a stepper motor is going to be anywhay fast enough to control a couple of drops of dispensed resin.  Pnuematically actuated valves (as Hood suggested) is definitely the way to go.

I made a dosometric system for this. I push a button and mix 200ml,  throw it in a tank. the mixed Urethane resine is under presure 1 - 1.5 bar and this Urethane resine has to only one way out The valve. When the  100ml goes to 20ml I push a butoon & I mix another  200ml.

When you have to drop a very small drops like 1/10ml or 1/20 mil the Pnuematically actuated valves is not very percise.

I Will shot the system and I will come back with photos to see....