Hi, I'm new here! I'm designing a dispensing system with several liquids. The liquids need to be dispensed into a circular area about 3/8" (opening of a bottle). I'm looking for advice, and would like to share my two ideas: A single peristaltic pump where the tube is manually changed. Each liquid would have it's own tube. A pressurized system with a centrifuge and tube for each liquid. All but one centrifuge would be programatically opened to allow the liquid to be dispensed. Details: Not every liquid is used each time. There will eventually be about 500 liquids, currently ~100, and about 5 are used with each dispense. The liquids cannot be cross-contaminated. The precision must be accurate to roughly 0.025mL (about one drop of water) if not possibly better. Some liquids are more viscous than others. The system will be controlled by an Arduino or Gadgeteer board for the dispensing volume. With plan A, I would calibrate the DC motor for the peristaltic pump by evaluating how many revolutions relates to volume. With Plan B, I would find an acceptable pressure, keep the system at that pressure, and would manually evaluate how much time the centrifuge being open relates to volume. (Since the viscosity varies, I more than likely will have to calculate this time each liquid). The hole in both of these plans are that I can foresee many problems related to accurate measurement. I hope I have adequately explained my puzzle! There may perhaps already be a solution to such a task that I am not aware of, but Google hasn't told me otherwise.