This is one technique for making braided rope in ZBrush. I posted this on Vimeo a couple years back but thought I would post it here as well. I’ve also included a step by step description.
Tutorial: Braided Rope or Cable using the CurveLineTube brush and a Cylinder Primitive.
Draw out a Cylinder3D and make the following adjustments
In Tool>Initialize subpallet:
Set X and Y size to 5; Set HDivide to 36 and VDivide to 128.
Click the MaskAll button; Set Select Count to 2 and Skip Count to 1; Click the Column button.
Inflate to 8 on X and Y axis only.
Clear the mask.
Make this object a PolyMesh3D.
Now in Tool>Geometry:
Divide one time.
Click the Mask By Cavity button; Click the GrowMask button one time.
Inflate to 8 on X and Y axis only; Inflate Ballon to 1 on X and Y axis only.
Clear the mask.
Twist to 100 on the Z axis only and repeat up to 10 times. Rename the tool to something like: Twist_Base.
Now in Tool>Geometry: Delete Lower Subdivisions.
Select the CurveLineTube brush.
Click on MeshInsert Preview and select the Twist_Base tool. Now the CurveLineTube brush is set to draw out a curve using the Twist_Base tool.
Now draw out a new primitive Cylinder3D and make the following adjustments in Tool>Initialize subpallet: Set X and Y Size to 5; Set HDivide to the number of strands you want the braided rope to be (i.e. 3 or 4).
Make this a PolyMesh3D and snap it in position by holding Shift while rotating the tool.
In the Transform pallet:
Click the Activate Symmetry button and select the Z axis; Turn on Radial Symmetry; Set Radial Count set to match the number of sides on the PolyMesh (i.e. 3 or 4).
Set a fairly large brush size and draw out a curve along the length of the PolyMesh. Adjust the brush size and click on one of the curve end points until the instances of the curve tube touch one another without overlapping or leaving a gap.
Twist to 100 on the Z axis only and repeat up to10 times. Rename the tool to something like RopeBraid_Base.
Click the Group Split button to separate the braided rope from the PolyMesh used to support the Curve Tubes. You can delete the support mesh leaving the braided rope.