Fabri-Solvy has several uses. It can be used as a design template to stitch through when quilting, monogramming, and using other similar crafting techniques. Just draw or trace your design onto the Fabri-Solvy with any kind of marker, position the design over the area to be stitched, hold it in place, and start stitching through the Fabri-Solvy into your fabric.
It can also be used as a stitching support piece, adding some stiffness and durability to your fabric during the actual embroidery, appliqué, or what have you. It can even be used as a fabric stiffener by dissolving some in water and painting it onto your fabric!
The best part of the product is that it is water soluble. Once you are done stitching your design through it, just cut away the excess, submerge your stitched design in water for a few minutes, and, just like that, the Fabri-Solvy trapped by the stitching dissolves and washes away.
Very cool stuff, very easy to use, and at this price there's no reason not to give it a try.