My laptop comes with a program called "Acer Recovery Management", which allows you to make a bootable recovery USB stick, from which you can boot to recover the computer to its original state.

Now, of course (I don't know why Acer didn't think about this) I don't want to give up a perfectly usable USB stick – which BTW needs to be at least 16 GB – to be a 'recovery disk' that I will probably never use anyway. But I still want to make it, just in case.

So, is there a way to convert the data on this bootable USB to an ISO file (or format), so that I can keep it on an external hard drive somewhere instead of a USB stick, and in case of problems convert the ISO back into a bootable USB with e.g. unetbootin?