This has been suggested before, but not for a while, and it seems to be something that most of the player base would like to happen and benefit from, so worth bringing up again (I think).
Just some sort of visual indicator on every machine that tells you the current status of the machine, without having to walk right up to it, point directly at it, or open the machine up.
I would suggest 4 states for the indicator.
Idle (not working, nothing in finished items)
Working (item in crafting queue, nothing in finished items)
Item ready (not working, finished item in storage)
Working + item ready (item in crafting queue + finished item in storage)
Not sure what form the indicator would take, it doesn’t really matter, the important thing would be that it was easily recognisable. So if I looked at a row of machines I could see the status of each without having to check each one individually.
This should apply to all ‘machines’, from the furnace to the forge.