The problem:

The amount of resources we accumulate in campaign greatly exceeds most ship's storage capacity so what people do is craft toolboxes, fill them and put filled toolboxes into lockers. After a few days of campaign, every locker looks like this: https://i.imgur.com/IkdYYdJ.png This is impractical to use because you can't see what is inside until you mouseover, you have to pick up a toolbox and take materials out in order to craft something (many fabricators are set up to draw materials from a locker but the feature is seldom used because it can't draw things from a toolbox inside the locker.

The solution:

Make items of the same kind stackable up to 12 but only inside submarine lockers. Toolboxes and player inventory can remain the same and you shouldn't be able to stack toolboxes together or large weapons like shotguns. This would make resource management easier and more enjoyable without upsetting the game balance in any way. You could also add a feature to shift click the stack which would put all of it into your inventory / crate you're holding / opened toolbox in inventory.

In the unstable build, toolboxes now hold 6 items.

Agreed on the problem. The suggested solution could work, but there's a simpler solution:

1. Just quadruple cabinet storage—large cabinets should be huge.
2. Make toolboxes like duffle bags: single hand, cannot go in inventory or other containers. They'll still be useful while carrying a screwdriver or wrench, but won't be exploited as magic item compactors. #Immersion

Likewise I'd suggest either removing the 3 storage slots on medical clothing, or else giving every job's clothing 3 slots (for job-specific gear only: tools, bottles, extra ammo, pipe/harmonica/PDA ).