Cool project!

I was just thinking about doing something like this today.
creating backup is easy just follow the steps below:

Open win32 disk imager.
Select correct drive.
click the folder icon.
navigate to where you would like to save image.
enter name of image e.g. retropie 2.6 configured.
click open.
select read.
done.

depends on how different the hardware is I guess, slight mods should rectify issues.

Meat