Carving intertwined or knotted stone designs requires a blend of technical skill, artistic vision, and patience. These complex patterns, often seen in Celtic knots or decorative reliefs, demand specialized approaches to achieve flawless results.

1. Tool Selection: Begin with high-quality tungsten carbide chisels for precision work. For tight curves in knots, use rifflers and needle files. A flexible shaft grinder helps refine intricate areas.

2. Design Transfer: Create a detailed 3D model or clay maquette first. Use transfer paper or scribe lines directly onto the stone surface, marking depth zones for overlapping sections.

3. Layered Carving: Work from the center outward in intertwined designs. Remove background material first, leaving the knotwork slightly raised. For true 3D knots, alternate between top and bottom strands to maintain proportional depth.

4. Undercutting Technique: Master the 45-degree undercut to create the illusion of strands passing beneath each other. This requires controlled mallet strikes and frequent visual checks from multiple angles.

5. Surface Refinement: Polish inner curves with diamond burrs before final sanding. For marble or alabaster, use pumice powder for a translucent effect in thin overlapping sections.

Pro tip: When working with harder stones like granite, consider modern methods like diamond wire cutting for initial separation of knot elements before hand-finishing. Always carve "in the round," rotating the piece constantly to maintain balanced tension in the design.

The key to success lies in understanding stone grain direction to prevent breakage in delicate areas. With practice, these techniques allow stone artists to create breathtaking dimensional illusions of infinite complexity.