I want to drop/paste/etc a blueprint into FP and it get turned into a [sub]factory with all the assemblers/smelters/etc and their recipes and modules and beacons and such.

With neither this nor my other parallel feature request, I find myself wasting a lot of time going through the same long process of selecting a bunch of recipes twice, once in FP and once in my assemblers. Especially when making a mall where I have a large number of assemblers with unique recipes, rather than a small number of recipes repeated across many assemblers/smelters/etc.
Being able to import or export between the world/blueprints and FP factory descriptions would cut that time in half.

This idea has come up before, and while it would be very neat to have, it has a ton of edge cases that make my job implementing it and user's using it much less useful and more annoying than you'd think at first. Fully analyzing an existing setup like that is quite difficult to do. Some thoughts on why that it on this Trello card. There is also Rate Calculator, which does a similar (but simpler in some ways) job of this, and is likely enough for most people, which makes it less useful for me to add this to the mod.