![](http://www.ecns.cn/hd/2020/11/05/6a08eb5892b04d0c893f78dfe3ebc2c7.jpg)
Photo shows a boat that has been 3D-printed by Leiden physicists Rachel Doherty, Daniela Kraft and colleagues. From prow to stern it measures 30 micrometers, about a third of the thickness of a hair. (Photo/ICphoto)
![](http://www.ecns.cn/hd/2020/11/05/cd75b6b0718d47c3aeaa0a8fe9a26c14.jpg)
Photo shows a boat that has been 3D-printed by Leiden physicists Rachel Doherty, Daniela Kraft and colleagues. From prow to stern it measures 30 micrometers, about a third of the thickness of a hair. (Photo/ICphoto)
![](http://www.ecns.cn/hd/2020/11/05/953a073d41534ec7ad360945de24e729.jpg)
Photo shows a boat that has been 3D-printed by Leiden physicists Rachel Doherty, Daniela Kraft and colleagues. From prow to stern it measures 30 micrometers, about a third of the thickness of a hair. (Photo/ICphoto)