All the common intermediary parts are already in the base shield books. I think it would be easier to have a stock of them available as recommended by NPCs and then just consult your easy to read specific manual when accessing your storage.
I don't know about you but I suffer extreme information overload trying to scan through the myriad unhelpful lines to find the particular ones I need to use. For that matter since the various parts all have the same recipe between the different materials they can be made from it would be much better to have "shape x shield bands from iron, steel, bronze, or gold heated ingots on the anvil with a hammer" in one line rather than in 4 lines mixed in with a lot of other stuff. In the case where different materials become available at different skill levels the materials not yet possible can be left out of the description.
Seriously the way these books are presented is garbage. I started to make manuals that made sense from editable books and if I could keep them in mind then I would finish the lot and give them away to whoever wanted them.
You are talking about the saving of one book in inventory, you make all your parts from the parts book then you switch to assembly book, complete the work and in the meantime you have a handy reference that is fully legible to make sure you have enough parts for what you want to make.
I am sorry for the strong language but that is how I see it. I lose more time looking for the recipes I need for the parts than I ever would switching books. These books appear to be nothing but an unsorted database dump, it can't be that hard to add an 'order by' switch can it?
Really I know how hard the developers are working on this stuff and I am certain there are issues I do not understand, I just get frustrated.
