In analysing how to apply 3D printing to chemistry, Cronin wondered in the first instance if the essentially passive idea of a highly sophisticated form of copying from a software blueprint could be made more dynamic. In his lab, they put together a rudimentary prototype of a chemical 3D printer, which could be programmed to make basic chemical reactions to produce different molecules.
After a bit of trial and error, Cronin's team discovered that it could use a bathroom sealant as a material to print reaction chambers of precisely specified dimensions, connected with tubes of different lengths and diameters. After the bespoke miniature lab had set hard, the printer could then inject the system reactants, or "chemical inks", to create sequenced reactions.
The "inks" would be simple reagents, from which more complex molecules are formed.
The real beauty of Cronin's prototype system, however, is that it allows the printer not only to control the sequences and exact calibration of inks, but also to shape, from a tested blueprint, the environment in which those reactions take place.
See the full story here: http://www.guardian.co.uk/science/2012/jul/21/chemputer-that-prints-out-drugs?newsfeed=true