This is a question about the same magic explained in this one. I also explain the magic below.
In my fantasy novel, magic is a natural part of the world. It is not some mystical force shrouded in mystery, but rather backed by science (though only I, the author, know it's true workings).
In my world, magic is a force that by its nature changes living cells. It is similar to radiation, but different in the respect that it changes what the cell does, usually in a beneficial way. For example, if the cells of an eye were exposed to magic, the magic might make the eye also see infrared light.
There are those in my world who can control the change worked by the magic. (They can force the magic to make the eye see infrared light. They can also use magic to make that same eye go blind.)
Using this magic, could a tree be grown into a specific shape, or made to form specific things solely with its wood? My goal here is to have individuals (think elves) be able to grow a living tree into a house, building, tower, shelter, etc. If possible, I would also like them to be able to grow armor out of the tree - have the tree shape the armor and then pinch it off, like it would a dead leaf.
Let me be clear here. Control cannot be established over the cells. They can simply be altered, so that they produce different chemicals or react differently. You cannot, for instance, just take control of a vine and have it weave itself into a basket. It would have to be grown that way.
Would growing on this scale be biologically possible, and if so, how would it be done (what in the cell would need to be changed)?