Help measure a complex shape and create a stencil from it

Hi all. I am trying to measure a complex shape to create a 12v panel for a cavity in my car. I have already made a panel from trial and error, however, I would like for this panel to be exact and I am looking for a way to do so. Currently, I am thinking that maybe using lidar and the canvas app on the iPhone could be the way to go? And then to convert this scan to a measurement which could, in turn, be transformed into a stencil that I can cut out from wood. Please see attached the photos and let me know of any questions. Thanks!