I never had much luck making stencils with the double blade Xacto knife. I mostly bought templates when I saw a designs I like so I have a huge collection. If I need to change the size, I scan the template, then resize the photo of the template and print it. I use normal drafting tracing paper cutting them into the size I need then put the photo underneath the few layers and then stitch following the lines with no thread in the sewing machine. Undo the copies and continue till you have all that you need. You can then follow the dots that the sewing machine made.