type
  TCEItem= class
  public
    RowName: String;
    Name: String;
    MaxStackSize: FixedUInt;
    CompatableAmmunitions: array of FixedUInt;
    KnockbackResponseWeapon: Boolean;
    EncumbranceWeight: Single;
    ...
  end;

procedure TForm1.Button3Click(Sender: TObject);
var
  CEItemList: TList<TCEItem>;
  CEItem: TCEItem;
  JMain: TJSONArray;
  JItem: TJSONValue;
  Index: Integer;
...
begin
...
  CEItemList:= TList<TCEItem>.Create();
  try
    // Add 2 objects to the list for testing purpouse
    CEItem:= TCEItem.Create;
    CEItem.RowName:= 'RowName 0';
    CEItem.Name:= 'Name 0';
    CEItem.MaxStackSize:= 6543;
    CEItem.KnockbackResponseWeapon:= True;
    CEItem.EncumbranceWeight:= 23.46;
    SetLength(CEItem.CompatableAmmunitions, 3);
    CEItem.CompatableAmmunitions[0]:= 50;
    CEItem.CompatableAmmunitions[1]:= 60;
    CEItem.CompatableAmmunitions[2]:= 70;
    CEItemList.Add(CEItem);

    CEItem:= TCEItem.Create;
    CEItem.RowName:= 'RowName 1';
    CEItem.Name:= 'Name 1';
    CEItem.MaxStackSize:= 3456;
    CEItem.KnockbackResponseWeapon:= False;
    CEItem.EncumbranceWeight:= 10.46;
    SetLength(CEItem.CompatableAmmunitions, 3);
    CEItem.CompatableAmmunitions[0]:= 10;
    CEItem.CompatableAmmunitions[1]:= 20;
    CEItem.CompatableAmmunitions[2]:= 30;
    CEItemList.Add(CEItem);

    // Create the main array
    JMain:= TJSONArray.Create;
    try
      // Add items objects to the main array
      for Index := 0 to CEItemList.Count-1 do
      begin
        JMain.Add(TJson.ObjectToJsonString(CEItemList.Items[Index]));
      end;

      formJSON.Lines.Text := JMain.ToJSON; // convert to a JSON string

    finally
      JMain.Free;
    end;

  finally
    CEItemList.Free;
  end;
...