Drag a finish from the library onto a surface, or click a surface and then a finish's “Use on…” button. Linked surfaces change together; hold Alt while dropping, or drop onto a row on the right, to change just one. Colours are the tiles' calibrated photos under flat, even light: compare palettes here, then render the finalists in Blender. Your palette stays in this browser; to keep it or render it, use Copy for Blender and paste it to Claude, and it becomes a scheme in the model.