Felting Tube Baguettes

Because the baguette is constructed with an open top, it is a bit of a challenge to felt in such a way that stripes don't flare out toward the circular ends. The top (of this and really all other bags) flares somewhat because there is nothing for those stitches to work against. As a result, the stitches do not felt as tightly as the rest of the bag body. There are, however, a few things you can do (singly or in combination) to mitigate this natural tendency:

Felt it tight: The simplest way to combat this flair is to felt your baguette very tightly and keep an eye on it during the felting process in order to check any creases and ensure even felting over the body.
Continue felting the portion of the bag that is flaring at the top: I had a student who owned a top-loading washer that would continue to agitate even though the lid was open. She stuck in the portion of her bag that was not as tightly felted as the rest and checked it often. Worked like a charm!
Sew the top together: Using a polyester or other synthetic thread, sew the top together after the bag has started to felt a bit, careful to line up any stripes. If the two sides felt together a little, it does not matter. Simply snip with a pair of sharp scissors when felting is complete and before blocking.

Blocking Tips

You can also help limit the flaring of the top opening and stripes during the blocking process and while sewing in the zipper:

Ease or Squeeze the Stripes/Top Opening While Blocking: You can use fishing line or a double strand of polyester sewing thread to ease the top of your baguette, again careful to match up stripes across the opening. Pack the body with newspaper or other packing material in order to give the bag shape and then sew the opening closed, matching stripes. Cut after the bag has dried completely.
Limit the Flare by Squeezing Stripes When Sewing In Zippers: You can take care of some of the flare when you sew a zipper into the top by squeezing or easing the felt and matching stripes.

Giving Your Baguette Shape

One of the wonderful things about the tube baguette is its crisp shaping, even when it is full of stuff! You can help your baguette look and stay fabulously crisp in several ways:

Give Your Bag Shape by "Lining" it With a Stiffener: Use a stiffener, such as an extremely heavy interfacing, to give your bag a nice, crisp tube shape. I prefer, however, to use plastic needlework canvas. It is inexpensive and if you can't get a sheet that is large enough to fit in your bag, then use more than one sheet, overlapping about two-three inches to avoid an unattractive seam. For the bag ends, either purchase precut circular canvases and cut to fit, or cut circles out of a regular sheet of the plastic canvas. In the case of both the bag body and the bag ends, it is important to tack the canvas into your bag at all edges and throughout the body. I use long running stitches with a double-strand of polyester thread.
Use a Large Zipper to Close the Top Opening of Your Bag: There are some wonderful zippers with different colored teeth that are available today. These can make the top of your bag very interesting and give it a special panache. A large-toothed plastic zipper in a solid color works well also and is significantly less expensive. Choose a zipper that is longer than you need. You can always cut to fit (after you have secured the end at the length you need). I recommend hand sewing in zippers using small stitches in thread that matches the bag itself. Pin one side first and sew in. Then close the zipper and pin the other side, making sure to match stripes. Unzip and sew in this second side.