Model the tree trunk

1. Create a NURBS cylinder, create lattice. Twist and pull the lattice point into the basic shape I want. When done, delete history to remove deformer. (Figure 1)

(Figure 1)

2. Then I want the tree trunk to build with deference surfaces. I then select all isoparm of the surface, and go to curve, duplicate surface curve. After I had duplicated the surface curve. I delete the NURBS cylinder, as well as horizontal curves. So I have something like this. (Figure 2)

(Figure 2)

3. I will then loft few curves to form surfaces. After the surfaces formed, keep pulling the CVs so that it look like tree trunk. This tree trunk is formed by 4 surfaces. (Figure 3)

(Figure 3)

4. Next, I'll detach surface in the front to make an opening for door. (Figure 4)

(Figure 4)

5. Now I will create the irregular shape of tree trunk to make it look like broken part. Select any one surface, pick the top edge isoparm, then duplicate surface curve. (Figure 5)

(Figure 5)