As the comments have already said, it is usual to use the words "undone" and "do up" only in relation to objects that can physically be joined or opened in some way, but there are exceptions. The usual usage is with buttons on clothing, laces on shoes, zip fasteners, string or tape around a package (although wrap and unwrap are more common) or knots in rope.
For things like your paper picture you would use unfinished, incomplete or even "not done".
The picture is unfinished [hasn't been done / coloured in], please complete it.
Many variations with the same or similar meaning are possible.
Your second example is definitely not right. It should be something like
The project/the food/ the task is incomplete [has not been
completed / finished], I have to finish it.
The comment about "I am undone" is a special and rather archaic English usage meaning I have lost everything (a fight, money, reputation or similar misfortune) and has no relevance to clothing or parcels!