On your server, each endpoint's files are stored in a directory that bears the endpoint's name. Usually it's under a folder called /RBS/
You can copy all that data to a USB drive and send it to your customer. After you copy the data, build the Disk Restore Utility and copy it to the drive, too. (That's a single .EXE file that you build like you build the Client installers.)
Your customer just needs to plug in the USB drive and run the .EXE program to install the Disk Restore Utility, and then follow instructions on the utility. It will be able to restore the data directly from the USB drive.