This is desperately needed. Both in terms of ship designed ships in the general sense, but also when attaching limited use upgrade precursor elements to a single ship.
It's a bit ridiculous to have to design a whole new ship in order to incorporate a single precursor missile pod I get from an event where I chose pragmatic or benevolent from a precursor site or planet.
I should be able to retrofit a current ship and just add on the precursor weapon.
Also, precursor weapons really need to get more advantage for their respective categories. Currently, I have that precursor missile pod and a couple others, but they're all outclassed by later tech by the time I was motivated enough to open up the ship designer and learn how to attach them. At the very least, they should have uniquely reduced mass, so that there's a good chance you can toss one of these weapons on an existing ship.