public Material Material {get; set;}

// 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

var sr = MapView.Active.Map.SpatialReference;

var extent = MapView.Active.Extent;
var center = extent.Center;
var centerZ = MapPointBuilderEx.CreateMapPoint(center.X, center.Y, 500, sr);

// cube
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Cube, centerZ, 200, sr);
// tetrahedron
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Tetrahedron, centerZ, 200, sr);
// diamond
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Diamond, centerZ, 200, sr);
// hexagon
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Hexagon, centerZ, 200, sr);

// sphere frame
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.SphereFrame, centerZ, 200, 0.8, sr);
// sphere
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Sphere, centerZ, 200, 0.8, sr);
// cylinder
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Cylinder, centerZ, 200, 0.8, sr);
// cone
multipatch = ArcGIS.Core.Geometry.MultipatchBuilderEx.CreateMultipatch(MultipatchConstructType.Cone, centerZ, 200, 0.8, sr);


// use the builder to add materials or textures
//   - create a cone with a material
builder = new MultipatchBuilderEx(MultipatchConstructType.Cone, centerZ, 200, 0.8, sr);

BasicMaterial faceMaterial = new BasicMaterial();
faceMaterial.Color = System.Windows.Media.Color.FromRgb(255, 0, 0);
faceMaterial.Shininess = 150;
faceMaterial.TransparencyPercent = 50;
faceMaterial.EdgeWidth = 20;

foreach (var patch in builder.Patches)
  patch.Material = faceMaterial;

multipatch = builder.ToGeometry() as Multipatch;