Warp Add/Sub Tools

Drag with the Warp Add tool to add bulk to a model. Select this tool and the cursor becomes: .

The Warp Sub tool, can be picked from the tools panel or just use the RMB while using the Warp Add tool to remove bulk from the model.

Tool Settings

The strength of the effect is effected by the warp size and intensity. The shape of the effect can be changed on the widgit warp panel - shown here: Drag on the Shape image to change the shape of the effect (To make sharp or flat changes as you paint). Drag the Intensity slider to change the strength of the effect. Hold CTRL and drag the LMB to change the Size of the effect (Or use the Warp Size Tool).

Examples

Make sure your mesh has a high resolution - this is needed to get good detail out of the warp tools. This test model has had its resolution increased to 8000 in the object properties panel.
When you first use the warp tool on a model you may be asked to convert the model to a mesh. This means you lose control over the object through its curves, but instead you can pull and push it in any direction using the warp and widgit tools. Here I have painted three dots on the model, they stick up towards the view direction they were painted in, eg: Painting in the front view will give bumps that stick straight forwards.
You can rotate the perspective view to warp the object in different directions. Painting longer strokes by dragging the LMB or RMB makes ridges and furrows on your model.
Use the RMB or pick the Warp Sub tool to remove bulk and poke depressions into your model.