Using barcodes to label and identify everyday items is as familiar as a trip to the supermarket. Imagine shrinking those barcodes a million times, from millimeter to nanometre scale, so that they could be used inside living cells to label, identify and track the building blocks of life or, blended into inks to prevent counterfeiting. This is the frontier of nanoengineering, requiring fabrication and controlled manipulation of nanostructures at atomic level—new, fundamental research, published in Nature Communications, shows the possibilities and opportunities ahead.