ToDataTable.cs

    public static class DataTableExtensions
    {
        public static DataTable ToDataTable<T>(this IEnumerable<T> data)
        {
            var properties = TypeDescriptor.GetProperties(typeof(T));
            var table = new DataTable();

            foreach (PropertyDescriptor prop in properties)
            {
                var name = prop.Name;
                var type = Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType;

                table.Columns.Add(name, type);
            }

            foreach (var item in data)
            {
                var row = table.NewRow();
                foreach (PropertyDescriptor prop in properties) row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
                table.Rows.Add(row);
            }

            return table;
        }
    }