So what if there's an app? Copying keys has been done for centuries and it's trivial. I forgot my personal storage locker key once at home when working at one metal company. It didn't take too long to call my dad, as details about the key, and creating a working copy. It was a Abloy Classic key, so it was trivial to copy of it from bolt using lathe and a bandsaw. With some key types you might also need a drill. All this work can be done bit slower using plain hand tools, you don't need even electric power for copying keys. And the lathe was only needed, because I naturally didn't have a right 'blank'. Copying keys has been always trivial if you have access to key you want to copy. I guess it's now ok to confess that I also had a teachers set of keys at school. Of course a copied set. One teacher borrowed me their keys once, and that's it. And this was 20 years ago and before copying the keys needed for personal locker at work.