The best way to extrude a vertices 3D model is to select the target vertices (or connected edges/faces for mesh stability) and use your 3D software’s extrusion tool to extend them along an axis, preserving the model’s structure.
This creates new linked geometry, ideal for adding details like buttons, ribs, or indentations without breaking the mesh.
For beginners, practice with a simple cube in Blender: select 2–3 top vertices, press "E" (extrude), and drag along the Z-axis—you’ll see the mesh expand smoothly while maintaining integrity.