The Stream Deck Key Creator is used to create icons for your SD buttons. Did you also know that it can create a wallpaper for your SD? Just select wallpaper mode (above the compose window).
You can then feed Key Creator an image and the app will break it up into the number of buttons required for your deck. You will receive individual png files numbered left to right, top to bottom. Add Open buttons, or whatever action you want to use, and drag and drop the pngs into place. Maybe pick a few to run your super secret spy apps. You can change the graphic on the Back button and it will still function fine.