This week we don't have a lab, but in lecture we learned about the state of the art for DNA nanostructures, i.e. DNA oragami. William Shih gave a pretty amazing overview, and I found a similar lecture by him on YouTube.
Holliday junction: the cross-shaped structure that forms during the process of genetic recombination, when two double-stranded DNA molecules become sepatated into four strands in order to exhcange segments of genetic information.
This figure from Cell Research shows inter-homologue mitotic junctions in recombinational repair.
Reference CAD tools: cadnano
These elements can make the following structural primitives by self latching to form sheets, skipping teeth to form angles, or combinations of these and folding out of plane.