researchers speed up two photon laser tweezers 3d printing

3-D printing technique accelerates nanoscale fabrication 1000-fold https://phys.org/news/2019-10-d-technique-nanoscale-fabrication-fold.html

Researchers use femtosecond lasers to speed up two-photon laser tweezers. They've shown the ability to get below the diffraction limit. I can only wonder what could keep them from getting further down to say one or two nano-meter, instead of a 125 nanometers.

The two photon laser tweezers work with polymerization. One could say that they arrange already atomic precise molecular structures. As they say, " The process, which can generate 3-D features smaller than the diffraction-limited, focused light spot, requires that two photons hit the liquid precursor molecules simultaneously."