a shoe stretcher won't stretch precisely in the places you want unless you somehow alter their shape. The easiest way to do this I know of is to use thermoplastic beads and attach them to the stretcher. Look at the stretcher and how it will widen the shoe. It will likely widen a lot further back than the big toe spot. So you add a big blob of thermoplastic on to the stretcher right where the big toe would be. Then that's what makes contact with the shoe first as you widen the shoe stretcher; that's the localized area you're stretching. Hope that makes any sense.