Can I Create My Own File Extension That Self-Deletes?

Technically, you don't need a new file extension for this. If it’s just for personal use, you could set up a cron job to manage files with a specific regex pattern and remove them after a set time. But if you want to share it, that's where it gets complicated. Though you could embed an image in an executable file that self-destructs after use, remember people can still take screenshots or save it if they're determined.

Creating your own file extension is totally doable! There's no law against it, so go for it! Just be careful not to use an extension that’s already widespread, to avoid any confusion. For making your file erase itself, you'll need to have a program that regularly checks for files of your custom extension and deletes them after a certain time frame. If you want it to auto-delete on its own without external scripts, that's trickier, but you could explore built-in methods in programming to implement that behavior, though it may not be foolproof.