public void CreateWallTypeFiltersTemplate() {
  UIDocument uidoc = this.ActiveUIDocument;
  Document doc = uidoc.Document;
  using(Transaction t = new Transaction(doc, "Create WallType Filters Template")) {
    t.Start();

    // 1. Collect wall types + Type Marks
    List < string > typeMarks = new List < string > ();
    var wallTypes = new FilteredElementCollector(doc)
      .OfClass(typeof (WallType))
      .Cast < WallType > ();

    foreach(WallType wt in wallTypes) {
      Parameter p = wt.get_Parameter(BuiltInParameter.ALL_MODEL_TYPE_MARK);
      if (p != null) {
        string val = p.AsString();

        if (!string.IsNullOrEmpty(val) && !typeMarks.Contains(val)) {
          typeMarks.Add(val);
        }
      }
    }

    if (typeMarks.Count == 0) {
      TaskDialog.Show("Error", "No Type Marks found.");
      t.RollBack();
      return;
    }

    // 2. Get Solid Fill pattern

    FillPatternElement solidFill = null;
    foreach(FillPatternElement f in new FilteredElementCollector(doc).OfClass(typeof (FillPatternElement))) {
      if (f.GetFillPattern().IsSolidFill) {
        solidFill = f;
        break;
      }
    }

    if (solidFill == null) {
      TaskDialog.Show("Error", "Solid fill pattern not found.");
      t.RollBack();
      return;
    }

    // 3. Create / get View Template

    View template = null;
    foreach(View v in new FilteredElementCollector(doc).OfClass(typeof (View))) {
      if (v.IsTemplate && v.Name == "Temp_ViewTypes") {
        template = v;
        break;
      }
    }

    if (template == null) {
      ViewFamilyType vft = new FilteredElementCollector(doc)
        .OfClass(typeof (ViewFamilyType))
        .Cast < ViewFamilyType > ()
        .First(x => x.ViewFamily == ViewFamily.FloorPlan);

      Level level = new FilteredElementCollector(doc)
        .OfClass(typeof (Level))
        .Cast < Level > ()
        .First();

      ViewPlan vp = ViewPlan.Create(doc, vft.Id, level.Id);

      vp.Name = "Temp_ViewTypes";

      template = vp;
    }

    // 4. Random generator
    Random rnd = new Random();

    // 5. Create filters + apply overrides

    foreach(string mark in typeMarks) {
      string filterName = "WallType_" + mark;

      // ---- Check existing filter
      ParameterFilterElement filter = null;

      foreach(ParameterFilterElement f in new FilteredElementCollector(doc).OfClass(typeof (ParameterFilterElement))) {
        if (f.Name == filterName) {
          filter = f;
          break;
        }
      }

      // ---- Create if not exists
      if (filter == null) {
        ElementId paramId = new ElementId(BuiltInParameter.ALL_MODEL_TYPE_MARK);

        FilterRule rule = ParameterFilterRuleFactory.CreateEqualsRule(paramId, mark, false);

        IList < FilterRule > rules = new List < FilterRule > {
          rule
        };

        // Wrap rules into ElementFilter
        ElementFilter elementFilter = new ElementParameterFilter(rules);

        IList < ElementId > categories = new List < ElementId > {
          new ElementId(BuiltInCategory.OST_Walls)
        };

        filter = ParameterFilterElement.Create(doc, filterName, categories, elementFilter);

      }

      // ---- Add filter to template
      if (!template.GetFilters().Contains(filter.Id)) {
        template.AddFilter(filter.Id);
      }

      // ---- Random color

      Color color = new Color((byte) rnd.Next(50, 255), (byte) rnd.Next(50, 255), (byte) rnd.Next(50, 255));

      // ---- Override settings
      OverrideGraphicSettings ogs = new OverrideGraphicSettings();

      ogs.SetCutForegroundPatternId(solidFill.Id);
      ogs.SetCutForegroundPatternColor(color);

      // optional (safer visually)

      ogs.SetCutBackgroundPatternId(solidFill.Id);
      ogs.SetCutBackgroundPatternColor(color);

      template.SetFilterOverrides(filter.Id, ogs);
      template.SetFilterVisibility(filter.Id, true);
    }

    t.Commit();
  }

  TaskDialog.Show("Done", "Template + filters created successfully.");
}