If you mean cutting a model without losing paint, the safest method is to plan the split before painting in CAD. After painting, use masking tape, score lines, and cut slowly with a sharp blade to reduce chipping. Adding alignment pins or joints also helps for clean reassembly.
For planning and estimation, tools like Painting Estimating Software, Commercial Painting Estimating Software, Paint Takeoff Software, Painting Takeoff Software, and Best Painting Estimating Software can help organize material usage and segmentation before work