Number keys hot bar.
An easy way to make building quicker and making combat more interesting would be to make the number keys (1-9) hot keys that you could quickly access items without having to open your inventory.
To assign numbers to items you must open your inventory, click the item you want to assign a number to and while holding left click, press any of the 1-9 keys (just like halving the amount of items in a trade window). When you press the number that the item is assigned to, it would do the same as opening your inventory, and clicking on it. This means that you must still look at your current item and click drop in order to place weapons on the ground.
(dam son) nice idea