public bool CullBackFace {get; set;}

// Create BasicMaterial with default values
BasicMaterial material = new BasicMaterial();
System.Windows.Media.Color color = material.Color;         // color = Colors.Black
System.Windows.Media.Color edgeColor = material.EdgeColor; // edgeColor = Colors.Black
int edgeWidth = material.EdgeWidth;                        // edgeWidth = 0
int transparency = material.TransparencyPercent;           // transparency = 0
int shininess = material.Shininess;                        // shininess = 0
bool cullBackFace = material.CullBackFace;                 // cullBackFace = false

// Modify the properties
material.Color = System.Windows.Media.Colors.Red;
material.EdgeColor = System.Windows.Media.Colors.Blue;
material.EdgeWidth = 10;
material.TransparencyPercent = 50;
material.Shininess = 25;
material.CullBackFace = true;

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(esriPatchType.Triangles);
patch.Coords = coords_face1;
patches.Add(patch);

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

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

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

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

patch = mpb.MakePatch(esriPatchType.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;