Special instructions for mint18:
linux-mint-18-t581.html#p5509Get the .deb files here for refractasnapshot. If you want to be able to install to hard drive from the pen drive, then you can also get refractainstaller.
http://sourceforge.net/projects/refracta/files/tools/Get mint set up the way you want, adjust the excludes file and the config file if you need to, run refractasnapshot, transfer the iso to usb using dd or cat, same as you would with any isohybrid image. See /usr/share/doc/refractasnapshot/readme and etc/refractasnapshot.conf.
If you did want persistence, or if you wanted a multi-boot usb, you could also get refracta2usb and use that to prepare the pen drive.