The character's pose depends a lot on the bottle so we will start by modeling a simple bottle. Then we will pose and build the character around it! We will try to keep the character as symmetrical as possible in the beginning, and break that symmetry at a later stage. Not a very conventional approach, but it will assure you that the relation between the character and the bottle will be perfect in the presentation shot.
Through the tutorial I will assume that you are using ZBrush 4, have installed some free plugins that can be downloaded at Pixologic and have set up GoZ to be connected with 3ds Max.
In 3ds Max, start by creating a rectangle with a height of 0.3m and a width of 0.035m in the Front viewport (Fig.03). Apply an Edit Spline modifier and insert two vertexes to define the shape of the bottle. Keep adding more vertexes and control the Bezier Splines at each vertex to shape the outer surface of the bottle. Delete the vertical line at the center and in Spline Sub-object mode select the remaining Spline and drag the Outline value to 0.003m in order to represent the thickness of the glass. Erase the lines at the top to create the bottle opening. Apply a Lathe modifier, turning on the Weld Core option and setting the align option to Min, so that the revolution axis is at the left margin of the half bottle section.
Move the bottle to make sure that the center of the base is at the 0,0,0 coordinates point. In the left view rotate the bottle 140 degrees counterclockwise to match the sketch (Fig.04). Even though we will export this bottle to ZBrush, save this editable version as you will need to tweak it later. With the bottle selected, from the GoZ menu choose GoZBrush.
ZBrush will open. For the bottle to show up, drag to the center of the screen and press the Edit button at the top. If you drag on the background while pressing Shift you are able to cycle through the orthographic views. Change to the front view facing the bottom of the bottle (Fig.05). From the Subtool menu choose Append and select the ZSphere. Decrease your brush radius to zero (as it is more practical to edit the ZSpheres) and select the ZSphere subtool. Press X to activate symmetrical editing. Move the ZSphere down to place it under the bottle (Fig.06).
While in Draw mode, if you drag on a ZSphere surface a new connected ZSphere will be created. If you drag at the symmetry line, a single ZSphere will be created, and if you drag on any other point of the ZSphere, two new symmetrical ZSpheres will be created. Use the Move and Scale modes to position the ZSpheres. If you click the chain between the two ZSpheres while in Draw mode, a new ZSphere is created at that point.
Using the ZSpheres create a form that approximates the character in the concept (Fig.07). Imagine that we are modeling the animal without the shell as that will be taken care of later. Start by growing the neck and snout from the base ZSphere as well as the main body shape. Refine the snout, body and neck by adding some extra ZSpheres. Grow a nose in front of the snout and add some ZSpheres in the place of the eyes and also grow a ZSphere on the top of the head to ensure that some more geometry will be generated there.