The Fold is used when bending a deformation further than the drawing is able to take it. This may result in an unwanted overlap of the line art at the junction of the articulation or deformation. The Fold will let you control certain parameters that will help eliminate the unwanted line effect.

To set up the Deformation-Fold effect module:

1. In the Camera view, enable Render mode to preview the fold. This will help you setup the Deformation-Fold effect as accurately as possible.
2. In the Network view, navigate to the deformation effect module causing the unwanted overlap. (In this case, an articulation)
3. In the Module Library, select a Fold module and drag it to the Network view. Note that the Fold module name changes to Deformation-Fold as it enters the Network view.
4. Connect the Deformation-Fold module directly under the deformation effect module which is causing the unwanted line effect.

5. In the Network view, select the Deformation-Fold module and select View > Show > Control to display its controls in the Camera view. Refer to Displaying the Deformation Controls for more display options.
6. In the Tools toolbar, select the Transform tool.
7. In the Camera view, setup the Deformation-Fold (you can also set these parameters directly in the Deformation-Fold Layer Properties):
Click on the fold axis and rotate it to match the angle of the bend articulation.

Use the middle arrow to position the axis along the deformer’s central line. It should be in the corner of the bending area.

Use the right and left arrows to control the appearance of the two overlapping lines.

Use the axis’ square handle to elongate or shorten the length of the axis.

8. If your character moves a lot and you need to adjust the fold at different positions to follow the limb animation, you can setup the Deformation-Fold effect in a different position over time. Do this by enabling the Animation mode in the Tools toolbar and adding keyframes. In this case, the different values will be connected to functions.
9. You can also enable and disable the Deformation-Fold effect over time by connecting a function to the Enable Fold parameter in the Layer Properties. A value of 1 enables the effect, a value of 0 disables the effect.