Chemists have learnt to assemble big molecules, like peptide, using smaller components. This process works well but it is difficult to apply if you are targeting small molecules, like those that make the basic substances in drugs.
There are a huge number of these small molecules and their syntheses, to evaluate their effectiveness as drugs, is complex, lengthy and costly.
This is where this news from the Howard Hughes Medical Institute, HHMI, comes in.
Researchers at the University of Illinois at Urbana Champaign led by Martin Burke, a former researcher at HHMI, have noticed that even in the case of small molecules there are some pattern (groups of atoms) that keep repeating. Hence they isolated hundreds of these patterns and created a 3D printer that can assemble them to create the desired molecule.
They foresee a time when a researcher will be able to ask the internet for the building blocks of a molecule, download them to a molecule 3D printer in his lab and get the desired molecule in a blink of an eye.
Making a small molecule today requires the invention of a set of chemic reactions leading to the syntheses of the desired molecule and this is really complicated. By having the possibility of building up the molecule everything gets easier.
Notice that this approach is fine if you are looking for a very limited number of molecules, which is what you usually need to test your hypotheses on its potential effect as a drug. Industrial production is quite a different story. There you will need billions of molecules and the additive process supported by a 3D printer no longer works.
At that time you will need to look for chemical reactions that can yield the desired molecules via syntheses. But at the point you will have confirmed that indeed that is the molecule you need.
Again we are seeing an unexpected use of a 3D printer (although a every special and complex one) in manufacturing. Also, this is a nanotechnology fabrication process, something unthinkable in the last century.