Seeing how much progress that Eikadistes has made on collecting the various translations of the Principal Doctrines makes me realize that it would truly be a worthy project to work on collecting the surviving excerpts from "On Nature." The only form in which I understand them to be accessible is in articles by David Sedley and a few others, but I don't even have a list of those articles, much less the core excerpts cut and pasted into a usable list.
Of course we can't and should not try to duplicate those full academic articles, but it would certainly be useful to produce a collection of the translated excerpts, noted as to the article/source from which they come, and listed (as best we can tell) in the right order.
This thread and subforum can be used to make notes on that by anyone who is interested in helping with this, and perhaps at some point someone like Nate can perhaps produce a PDF with the collection in better form.