Testing the syringe
First off this testing would never have been possible without the incredible assistance and help of Vincent Dean, Nurit Bar-Shai and Tom Igoe. Thanks!
Once I had come to the syringe idea, it was clear it would need real testing. First I experimented with various drug store droppers and syringes, and got a rough idea of what was needed. Next up was a scouring of science surplus catalogs until I found a few different syringes in bulk. I did additional tests with these to determine which appeared to be the best, in terms of size, precision, resulting drop size and drip resistance. I settled on one generic and rather inexpensive model, and worked on devising a test that would give a sense of what a working printer powering the syringe might produce.
What I ended up with was a program that generated numbered grids for each color. Black squares indicated what parts of the grid were to recieve each color. Then on painter's paper I drew a grid and then carefully applied the appropriate color to each grid square. Easier said than done, it was a long process and rather painful on the arm. Worth every minute though!