The product is In R Form Bosal Bag & General Foam Batting, which is rather a mouthful. The product description is: A unique fusible foam stabiliser/batting/wadding ideal for bag making. It is soft and formable, easy to stitch, and needle friendly. The foam gives stability and shape to your bags and other projects, whilst giving a really quite unique soft, padded feel.
There is a YouTube Video which demonstrates one way of using it to make bags, which I used as the basis of doing my bag.
I used my ordinary piecing foot for this stage with no problems whatsoever.
I love the finished effect and would use this technique again if I was making things for myself or as gifts. It's quite a time consuming process, so for items to be sold, it may not be as cost effective. Of course, it would be just as good without the extra quilting.
I used the batting for the handles and I did use the walking for for joining all the layers. This was more for ease, than necessity, the edge of the foot is just the right place to use as a seam guide.
When do the top stitching around the top of the bag, it might appear to be bulky, but it folds nicely and holds in place easily with clips. There was no issue with getting it through the machine.