Challenge #1: A LACK OF ATOMIC-lEVEL design rules

 The synthesis of functional nanoscale objects remains a largely trial-and-error endeavor. We do not have the fundamental chemical knowledge needed to a priori control structure and properties. 

Challenge #2: Scale-up is harD 

Future technologies will require large quantities -- tons rather than grams -- of nanoscale objects from which to build new materials and devices. Attempts to scale production usually sacrifice structural fidelity and destroy function. 

Challenge #3: AssemblY is very hard

The production of macroscopic materials and devices via the assembly of nanoscopic building blocks, each with tailored properties, has been a long-standing goal. Processes to do this with the necessary speed, precision, and error-tolerance do not exist.