I don't know what "Chipboad" is, I probably call it something else. Extracting the pages from the .pdf and then darkening with the appropriate program would be the best way. Personally, I think having the faintest lines you can work with gives you a better looking mode. I believe that may have been what David Lukens had in mind, looking at the care and effort put into this model. It's quite astonishing actually. I was able to extract the pages, but since it is locked in the .pdf, I will not share these .jpegs, nor tell anyone how to do it, anyone good with software can crack Adobe security. I would sincerely advise doing this only for your own purposes. I could import this into Rhino and create darker lines, if I had time to do anything but fix my house.
Maybe he will offer two versions, one with darker lines, and one with softer. I don't know what program he used to make this model, in some programs that is just a matter of changing the properties of all the lines, and "woomp", there it is. With other programs, not so easy.