What would you add to invest materials in?

I'm curious to hear others' opinions on where/what they would like to invest their ever increasing hoard of mats into if given a new opportunity.

I've had thoughts of more engaging fleet options that would include risk of loss, thus the need to rebuild sunken ships.

I've wanted our own pirate den to capture, build up, stock, maintain and defend.

I've entertained the thought of an expanded manufactory defense system. Where instead of any random manu being attacked and having to go though the painfully tedious current defense event. Each territory would have a main manufactory(capital, largest settlement, fort), and once that territory was controlled, it would be open to spawning a defense, but, they would be much more involved than the current system and you would have the opportunity to place fleet ships there and upgrade the defenses.

More involved crafting with actually lucrative sales and delivery contracts.

These are just some thoughts I've had, I'd like to hear what other people would choose to spend their mats on if they had the opportunity.