public new Multipatch ToGeometry()

var coords_face1 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495461061000071,41.902603910000039,62.552700000000186),
  new Coordinate3D(12.495461061000071,41.902603910000039,59.504700000004959),
  new Coordinate3D(12.495461061000071,41.902576344000067,59.504700000004959),
  new Coordinate3D(12.495461061000071,41.902603910000039,62.552700000000186),
  new Coordinate3D(12.495461061000071,41.902576344000067,59.504700000004959),
  new Coordinate3D(12.495461061000071,41.902576344000067,62.552700000000186),
};

var coords_face2 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495461061000071, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495461061000071, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 62.552700000000186),
};

var coords_face3 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495488442000067, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 62.552700000000186),
};

var coords_face4 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495488442000067, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 59.504700000004959),
};

var coords_face5 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495488442000067, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 59.504700000004959),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 62.552700000000186),
};

var coords_face6 = new List<Coordinate3D>()
{
  new Coordinate3D(12.495488442000067, 41.902603910000039, 62.552700000000186),
  new Coordinate3D(12.495461061000071, 41.902603910000039, 62.552700000000186),
  new Coordinate3D(12.495461061000071, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902603910000039, 62.552700000000186),
  new Coordinate3D(12.495461061000071, 41.902576344000067, 62.552700000000186),
  new Coordinate3D(12.495488442000067, 41.902576344000067, 62.552700000000186),
};

// materials
var materialRed = new BasicMaterial();
materialRed.Color = System.Windows.Media.Colors.Red;

var materialTransparent = new BasicMaterial();
materialTransparent.Color = System.Windows.Media.Colors.White;
materialTransparent.TransparencyPercent = 80;

var blueTransparent = new BasicMaterial(materialTransparent);
blueTransparent.Color = System.Windows.Media.Colors.SkyBlue;

// create a list of patch objects
var patches = new List<Patch>();

// create the multipatchBuilderEx object
var mpb = new ArcGIS.Core.Geometry.MultipatchBuilderEx();

// make each patch using the appropriate coordinates and add to the patch list
var patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face1;
patches.Add(patch);

patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face2;
patches.Add(patch);

patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face3;
patches.Add(patch);

patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face4;
patches.Add(patch);

patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face5;
patches.Add(patch);

patch = mpb.MakePatch(PatchType.Triangles);
patch.Coords = coords_face6;
patches.Add(patch);

patches[0].Material = materialRed;
patches[1].Material = materialTransparent;
patches[2].Material = materialRed;
patches[3].Material = materialRed;
patches[4].Material = materialRed;
patches[5].Material = blueTransparent;

// assign the patches to the multipatchBuilder
mpb.Patches = patches;

// check which patches currently contain the material
var red = mpb.QueryPatchIndicesWithMaterial(materialRed);
//   red should be [0, 2, 3, 4]


// call ToGeometry to get the multipatch
multipatch = mpb.ToGeometry() as Multipatch;

// create the multipatchBuilderEx object
var builder = new ArcGIS.Core.Geometry.MultipatchBuilderEx(multipatch);

// check some properties
bool hasM = builder.HasM;
bool hasZ = builder.HasZ;
bool hasID = builder.HasID;
bool isEmpty = builder.IsEmpty;
bool hasNormals = builder.HasNormals;

var patches = builder.Patches;
int patchCount = patches.Count;

// if there's some patches
if (patchCount > 0)
{
  int pointCount = builder.GetPatchPointCount(0);

  // replace the first point in the first patch
  if (pointCount > 0)
  {
    // get the first point
    var pt = builder.GetPoint(0, 0);
    builder.SetPoint(0, 0, newPoint);
  }

  // check which patches currently contain the texture
  var texture = builder.QueryPatchIndicesWithTexture(brickTextureResource);

  // assign a texture material
  patches[0].Material = brickMaterialTexture;
}

// update the builder for M awareness
builder.HasM = true;
// synchronize the patch attributes to match the builder attributes
//   in this instance because we just set HasM to true on the builder, each patch will now get a default M value for it's set of coordinates
builder.SynchronizeAttributeAwareness();

// call ToGeometry to get the multipatch
multipatch = builder.ToGeometry() as Multipatch;

// multipatch.HasM will be true