I use stencils all the time. I either use powder white chalk or a purple be gone. When I need to alter the stencil size, I draw it out, scan it, make the size change and the print it out on thinnest copy paper. Then I cut tracing paper and put that behind the copy. Take thread and bobbin out and stitch on the line as accurate as possible. Then I take the punched tracing paper pinning it in place where I want to quilt and use that as my template quilting as I go. Then gently remove the tracing paper and it is done.