This script creates a new mesh from active object’s tessfaces. It can be used to make the tessellation visible.
copy_tessfaces() uses bmesh module, which is rather slow, copy_tessfaces_faster() uses a Mesh directly (polys, loops…) and works a lot faster on complex models.
Dunno if this is any useful, maybe use it as example how to create a mesh with polygons and loops 
import bpy
def copy_tessfaces():
ob = bpy.context.active_object
if ob is None:
return
if ob.type != 'MESH':
return
bpy.ops.object.mode_set(mode='OBJECT', toggle=False)
me = ob.data
me.update(calc_tessface=True)
import bmesh
bm = bmesh.new()
for v in me.vertices:
bm.verts.new(v.co)
for e in me.edges:
bm.edges.new((bm.verts[e.vertices[0]], bm.verts[e.vertices[1]]))
for tf in me.tessfaces:
try:
if len(tf.vertices) == 3:
bm.faces.new((bm.verts[tf.vertices[0]],bm.verts[tf.vertices[1]],bm.verts[tf.vertices[2]]))
else:
bm.faces.new((bm.verts[tf.vertices[0]],bm.verts[tf.vertices[1]],bm.verts[tf.vertices[2]],bm.verts[tf.vertices[3]]))
except ValueError:
# e.g. face already exists
continue
mesh = bpy.data.meshes.new("Tessface Cache")
bm.to_mesh(mesh)
o = bpy.data.objects.new("Tessfaces Copy", mesh)
#o.location = bpy.context.scene.cursor_location
#o.location = ob.location
o.matrix_world = ob.matrix_world
o.draw_type = 'WIRE'
o.show_x_ray = True
bpy.context.scene.objects.link(o)
bpy.ops.object.select_all(action='DESELECT')
o.select = True
bpy.context.scene.objects.active = o
bpy.context.scene.update()
def copy_tessfaces_faster():
ob = bpy.context.active_object
if ob is None:
return False
if ob.type != 'MESH':
return False
bpy.ops.object.mode_set(mode='OBJECT', toggle=False)
me = ob.data
me.update(calc_tessface=True)
mesh = bpy.data.meshes.new("Tessface Cache")
mesh.vertices.add(len(me.vertices))
verts = []
for v in me.vertices:
verts.extend(v.co)
mesh.vertices.foreach_set("co", verts)
mesh.edges.add(len(me.edges))
for e in me.edges:
mesh.edges[e.index].vertices = e.vertices
#loop_count = len(me.loops)
loop_count = sum(len(tf.vertices) for tf in me.tessfaces)
mesh.loops.add(loop_count)
mesh.polygons.add(len(me.tessfaces))
l = 0
for tf in me.tessfaces:
mesh.polygons[tf.index].loop_start = l
mesh.polygons[tf.index].vertices = tf.vertices
mesh.loops[l].vertex_index = tf.vertices[0]
mesh.loops[l+1].vertex_index = tf.vertices[1]
mesh.loops[l+2].vertex_index = tf.vertices[2]
if len(tf.vertices) == 4:
mesh.loops[l+3].vertex_index = tf.vertices[3]
mesh.polygons[tf.index].loop_total = 4
l += 4
else:
mesh.polygons[tf.index].loop_total = 3
l += 3
mesh.validate()
mesh.update()
o = bpy.data.objects.new("Tessfaces Copy", mesh)
o.matrix_world = ob.matrix_world
o.draw_type = 'WIRE'
o.show_x_ray = True
bpy.context.scene.objects.link(o)
bpy.ops.object.select_all(action='DESELECT')
o.select = True
bpy.context.scene.objects.active = o
bpy.context.scene.update()
if __name__ == "__main__":
# Run the faster method
#copy_tessfaces()
copy_tessfaces_faster()