I have a Xubuntu in my VirtualBox machine with several changes, and I'd like to make a LiveUSB out of it.
I've already heard about Remastersys, but it's not supported anymore. How to customize the Ubuntu Live CD? explains how to customize a LiveCD but it needs an ISO as a base, I can't use an existing installation.
Relinux
also seems to be abandoned.
How can I create a Live USB from my Xubuntu installation?