Invisible Object (Small): I envision this as something that people could use to tag static things that are currently a part of the areas. For example carving some initials on a tree. I see many times where people make something like a road sign, or sign board and then hover it into something to do this. Additionally I see times where someone wants to graffiti someone else's fixture like painting a mustache on a statue or some other prank. I think doing either of these with the invisible object small would be more ideal. I would suggest making the input to crafting this just a coin cost as a small 'tax' that can help drain coin out of the economy.
Curtains: There are quite a few places where I see that people put up book shelves to define separate spaces with in a room or perhaps cover a door. Sometimes these bookshelves even get named as such like "room dividing shelf". I know that bookshelves are also path blocking which has been something of an issue in the past where people abuse something like that. I am pretty certain that all the curtain models are non-path blocking and could probably serve better than placing bookshelves all over the place to allow players to 'sandbox' larger rooms for their own purposes. These could just use iron ingots (for the rods) large clothes for the curtains and some dyes for the different colors to make.
Wall Torches: Another option that might be used in place of candles where some rooms are dark. Could require soft wood, iron ingots and oil.