After setting the UVs I attached the gums, teeth and eyes to the body mesh and exported it in OBJ format, which was then effortlessly imported into ZBrush (Fig.03).
With the mesh inside ZBrush, I used the Tools > Polygroups > Auto Groups option to easily separate all the elements into different Polygroups. Then in the SubTools menu I have chosen Group Split to automatically place each polygroup into a separate SubTool. This way, the eyes, gums and teeth were stored as individual SubTools.
The following step - a very important one - was to define the Polygroups of the main body. By separating the mesh in different groups you can hide/mask parts of the body during the sculpting stage. This allows you to reach inaccessible areas after posing and making selections for transposing a lot quicker. With the model in a T-pose it was very simple to make the selections to define the Polygroups. I defined the polygroups according to the anatomy of the body: head, torso, arms, forearms, hands, thighs, legs and feet (Fig.04). Later, for hand positioning, I also had to separate each individual finger into a Polygroup.
I usually use the Symmetry tool while sculpting for as long as I can, in order to minimize doubling the work in certain parts of the body; however, with this project it was not the case. The pose of the rabbit was my main concern and I wanted his muscles to bulge and shape correctly according to their final position, so I took the option of posing each body part first and shaping its anatomy later.
I used the Transpose tool for all the posing, mainly by masking the part I wanted to position, inverting the mask selection, setting the Transpose Action Line as if it was an actual bone, and rotating it around the joint (Fig.05). After rotating, it is common that the joint area doesn't deform exactly as you would like, but a few brushstrokes can usually fix that. The Polygroup distribution was really handy at this time, allowing for a fast selection.
Regarding the sculpting technique, there was nothing new about it, I mainly used the Move tool for reshaping, the Clay tool for sculpting (I find it more controllable than the Standard brush), the Inflat tool for muscle bulging, the Flatten tool to smooth the surface (I prefer it over the Smooth tool for this purpose), and the Smooth tool for untangling the surface when deformations get ugly - particularly at the inner parts of the joints after transposing, where geometry tends to self-intersect.
I've prepared an image in which you can see the evolution of the sculpting phase (Fig.06).