diff --git a/docs/changes.md b/docs/changes.md
index fc1fb69c..84957c05 100644
--- a/docs/changes.md
+++ b/docs/changes.md
@@ -59,6 +59,7 @@ examples/other/nelder-mead.py
 tests/issues/issue_968.py
 tests/snippets/test_discourse_1956.py
 tests/snippets/test_ellipsoid_main_axes.py
+tests/snippets/test_compare_fit1.py
 ```
 
 ### Broken Examples
diff --git a/tests/snippets/test_cell_types.py b/tests/snippets/test_cell_types.py
new file mode 100644
index 00000000..465ea6ef
--- /dev/null
+++ b/tests/snippets/test_cell_types.py
@@ -0,0 +1,176 @@
+from vedo import UnstructuredGrid, Points, show, settings, utils
+
+#####################################
+def makeTetrahedron():
+    """A tetrahedron"""
+    pts = [
+        (0, 0, 0),
+        (1, 0, 0),
+        (1, 1, 0),
+        (0, 1, 1),
+    ]
+    cells = [[0, 1, 2, 3]]
+    cellstypes = [10]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+#####################################
+def makeHexahedron():
+    """A regular hexagon (cube) with all faces square and three squares around
+    each vertex is created below.
+    Setup the coordinates of eight points (the two faces must be in
+    counter clockwise order as viewed from the outside).
+    """
+    pts = [
+        (0.0, 0.0, 0.0),
+        (1.0, 0.0, 0.0),
+        (1.0, 1.0, 0.0),
+        (0.0, 1.0, 0.0),
+        (0.0, 0.0, 1.0),
+        (1.0, 0.0, 1.0),
+        (1.0, 1.0, 1.0),
+        (0.0, 1.0, 1.0),
+    ]
+    cells = [[0, 1, 2, 3, 4, 5, 6, 7]]
+    cellstypes = [12]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+#####################################
+def makePyramid():
+    """Make a regular square pyramid"""
+    pts = [
+        [1.0, 1.0, 0.0],
+        [-1.0, 1.0, 0.0],
+        [-1.0, -1.0, 0.0],
+        [1.0, -1.0, 0.0],
+        [0.0, 0.0, 1.0],
+    ]
+    cells = [[0, 1, 2, 3, 4]]
+    cellstypes = [14]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+#####################################
+def makeWedge():
+    """A wedge consists of two triangular ends and three rectangular faces"""
+    pts = [
+        (0, 1, 0),
+        (0, 0, 0),
+        (0, 0.25, 0.25),
+        (1, 1, 0),
+        (1, 0.0, 0.0),
+        (1, 0.25, 0.25),
+    ]
+    cells = [[0, 1, 2, 3, 4, 5]]
+    cellstypes = [13]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+#####################################
+def makeHexagonalPrism():
+    """Hexagonal prism: a wedge with an hexagonal base.
+    Be careful, the base face ordering is different from wedge.
+    """
+    pts = [
+        (0.0, 0.0, 1.0),
+        (1.0, 0.0, 1.0),
+        (1.5, 0.5, 1.0),
+        (1.0, 1.0, 1.0),
+        (0.0, 1.0, 1.0),
+        (-0.5, 0.5, 1.0),
+        ####
+        (0.0, 0.0, 0.0),
+        (1.0, 0.0, 0.0),
+        (1.5, 0.5, 0.0),
+        (1.0, 1.0, 0.0),
+        (0.0, 1.0, 0.0),
+        (-0.5, 0.5, 0.0),
+    ]
+    cells = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]]
+    cellstypes = [16]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+#####################################
+def makePentagonalPrism():
+    """A 3D pentagonal prism: a wedge with an pentagonal base."""
+    pts = [
+        (11, 10, 10),
+        (13, 10, 10),
+        (14, 12, 10),
+        (12, 14, 10),
+        (10, 12, 10),
+        (11, 10, 14),
+        (13, 10, 14),
+        (14, 12, 14),
+        (12, 14, 14),
+        (10, 12, 14),
+    ]
+    cells = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]]
+    cellstypes = [15]
+    ug = UnstructuredGrid([pts, cells, cellstypes])
+    ug.c('w', 0.25).lw(2).lighting("off")
+    return ug
+
+
+def makeQuadraticTetra():
+    import vtk
+
+    print(utils.vtkVersionIsAtLeast(9))
+    aTetra = vtk.vtkQuadraticTetra()
+    points = vtk.vtkPoints()
+
+    pcoords = aTetra.GetParametricCoords()
+    rng = vtk.vtkMinimalStandardRandomSequence()
+    points.SetNumberOfPoints(aTetra.GetNumberOfPoints())
+    rng.SetSeed(5070)  # for testing
+    for i in range(0, aTetra.GetNumberOfPoints()):
+        perturbation = [0.0] * 3
+        for j in range(0, 3):
+            rng.Next()
+            perturbation[j] = rng.GetRangeValue(-0.1, 0.1)
+        aTetra.GetPointIds().SetId(i, i)
+        points.SetPoint(i, [pcoords[3 * i], pcoords[3 * i + 1], pcoords[3 * i + 2]])
+
+    ug = vtk.vtkUnstructuredGrid()
+    ug.SetPoints(points)
+    ug.InsertNextCell(aTetra.GetCellType(), aTetra.GetPointIds())
+    return UnstructuredGrid(ug)
+
+
+#####################################
+tetr = makeTetrahedron()
+hexa = makeHexahedron()
+pirm = makePyramid()
+wedg = makeWedge()
+hexp = makeHexagonalPrism()
+penp = makePentagonalPrism()
+# qtetr= makeQuadraticTetra()
+
+settings.immediate_rendering = False  # faster for multi-renderers
+
+show(
+    [
+        ["Tetrahedron", tetr, Points(tetr.vertices, r=15, c="o")],
+        ["Hexahedron", hexa, Points(hexa.vertices, r=15, c="o")],
+        ["Pyramid", pirm, Points(pirm.vertices, r=15, c="o")],
+        ["Wedge", wedg, Points(wedg.vertices, r=15, c="o")],
+        ["HexagonalPrism", hexp, Points(hexp.vertices, r=15, c="o")],
+        ["PentagonalPrism", penp, Points(penp.vertices, r=15, c="o")],
+    ],
+    N=6,
+    bg="blue3",
+    sharecam=False,
+    axes=1,
+).close()
diff --git a/vedo/version.py b/vedo/version.py
index 4ee35a49..fcf17404 100644
--- a/vedo/version.py
+++ b/vedo/version.py
@@ -1 +1 @@
-_version = '2023.5.0+dev15'
+_version = '2023.5.0+dev16'