All of the options above are exceptional ideas. I’d add in functional items like neodymium magnets for hold downs, or 3D printed risers for thicker materials when not using the crumb tray.
From a materials standpoint, non standard sized tiles from Lowes or Home depot would be a nice gift, and probably not something they might buy on their own. The tile projects are always fun, especially when it isn’t just a standard 4x4.