PittGaymer
Terrarian
Minecraft has an option for "pick block" in creative, which automatically generates a max stack of the item you click on. I think this would be helpful if you're building something, get distracted and do something else, removing the items from your inventory, then coming back to that project later. Instead of sorting and rooting through the duplication menu, I think it would be very beneficial to assign a key to duplicating a block you're hovering over, thus, being able to easily replicate what you were working on before. I'd find this VERY helpful during accidental destruction as well, say, fixing an area's aesthetics if someone went willy nilly with the drill containment unit.