quilt, duvet

My mother makes quilted blankets for charity along with many other women. Each resultant blanket, or quilt, or duvet, whatever you call it, consists of a layer of fabric on each side, sandwiching a thicker, fluffier filler material in the center, which can be wool or a synthetic equivalent, and this gives the blanket much warmth. They stitch right through the blanket with yarn by hand, so that this inner filler material is held in place. These stitches are separate from each other; it is not a continuous thread from one stitch to the other, but rather they double-stitch through, then cut the yarn and tie it each time. The pattern of these stitches is a grid which covers the entire blanket, with a space of a few inches between each one.

So, there are a lot of them and this is the most time-consuming phase of making a blanket. What would speed the whole process would be a machine which performed this stitching for them. It could even be something other than the yarn, but it must not be uncomfortable to user of the blanket and must be durable over many years of use. So, metal staples are out. Perhaps some type of "button" which pierces through and locks to a corresponding button on the other side. Dunno...

I hoped something in the upholstery industry might be available, but an inquiry at one shop which sells upholstery machines yielded nothing. Not that I think they know everything. I also searched a wee bit online, but found nothing. So, maybe someone can point me in the right direction, or come up with an invention or at least a good idea for one. Not sure how commercial duvets are made, but I should take a look next time I see one.