I used to work in the lab in question, though nowhere near this project. (And I'm ridiculously proud of my colleagues right now. :D ) To answer your question,

I used to work in the lab in question, though nowhere near this project. (And I'm ridiculously proud of my colleagues right now. :D ) To answer your question, setting the components on fresh ink is often sufficient but not always. IIRC, components were often put in place and then "drawn over" a second time with the pen, or small beads of ink were put in place. I saw cross-overs demonstrated simply using normal white-out (!) after the first trace was dry, but I no longer have access to a journal subscription so I'll have to bug my colleagues for a copy before I know if that is what was used in the publication.