The peachy printer doesn't move the build plate, if my understanding is correct. The saline level is increased as the print continues. There must also be some method to dispense an accurate amount of resin to compensate for the resin used and the desired layer thickness.

I agree about the uncertainty involved in the method. I believe it counts drops of saline that pass through a set of electrical contacts. I recognize that one can have accurate measurement to very high tolerances with drops, but I suspect that conditions have to be very carefully controlled to accomplish that. Evaporation, saline concentration, temperature, the relative humidity of the surroundings, all these are likely to be important. How important, only time will tell. My neighbor has contributed to the Kickstarter campaign, and I'm certain to learn when/if he receives his printer