You can use layers to sculpt on one side of a model and then copy the sculpting onto the other side of the model.

Using sculpt layers you can:

• Mirror the sculpting on a layer across the axis of symmetry when the object is symmetrical. For more information, see Mirror a sculpt layer on a symmetrical model.
• Mirror sculpting already completed on a layer when the shape or pose of the model is asymmetric, provided its topology is symmetric using the Tangent option. To use this feature you must first define the topological axis of symmetry.