I collect pretty much every construction material that I find during my journey and put it in the stash box. Piece by piece.
I think it would be a nice addition to have a button (like the autosort one) that transfers all construction materials from your inventory into your stash box.
I contacted Eric from GD team about this, the fastest way would be Shift-Click on an item. This will transfer it to stash, if it’s open. Keep holding Shift, 1 click per item, you save on dragging each one manually. To save a bit of effort, combine before doing this. Still not a single click, but better.