Sample 3D curve and capture normal & tangent vector attribute.

Splitting the spline into segments.

Adjustment of segment positions based on 3D noise.

Adding a profile to the curves and calculating UV.

Apply a shade smooth, a surface subdivision and a material. Then displace the faces along their normals using 3D noise.

Creating a 3D line and instantiating the mesh at each end of the curve's segments.

Apply a displacement to the 3D lines.

Adding a profile to the 3D line and calculating UV.

Added details to the top of the column and removed the bottom face.

Apply a shade smooth and a material. Then displace the faces along their normals using 3D noise.

All geometry node graph.

Initial mesh shape.

Distribute 2D planes on the geometry.

Apply the mesh normal to the instances.

All geometry node graph and checking for normal vector using a Fresnel effect.

An old geometry node I do a year ago following this video : https://www.youtube.com/watch?v=x18QCCuFy3k

Sample 3D spline.

Add a profile to the curve and define the radius along the curve.

Duplicate the curve with a new profile containing several individual circles and add a twist along the profile.

All geometry node graph.