This is an implementation of a disposable HtmlHelper extension

TableExtensions.cs.

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Web.Mvc;

namespace Demo.Helpers
{
    public static class TableExtensions
    {
        public static MultiColumnTableHelper BeginMultiColumnTable(this HtmlHelper htmlHelper, params string[] headers)
        {
            return new MultiColumnTableHelper(htmlHelper.ViewContext.Writer, headers);
        }

        public class MultiColumnTableHelper : IDisposable
        {
            private TextWriter _textWriter;

            public MultiColumnTableHelper(TextWriter textWriter, IEnumerable<string> headers)
            {
                _textWriter = textWriter;
                var htmlBuilder = new StringBuilder();
                htmlBuilder.Append("<table><thead><tr>");
                foreach (var header in headers)
                {
                    htmlBuilder.AppendFormat("<th>{0}</th>", header);
                }
                htmlBuilder.Append(@"</tr></thead>");
                _textWriter.Write(htmlBuilder.ToString());
            }

            public void Dispose()
            {
                _textWriter.Write("</table>");
            }
        }
    }
}