Use chalk or a piece of soap that is about used up. Fons and porter show a couple of weeks ago had a tip instead of using a pounce with chalk dust in it on a stencil, to use a foam paint bruch. Dip it into the chalk dust and then wipe over the stencil design you are using. They were using a commercial stencil template. I don't know if it would work if you were to make your design on paper, stitch through it on your sewing machine, and then lay it on the fabric and brushh over it. I do a lot of work with felted wool, but haven't done anything that required stitching on the interior of the wool pieces.