If you have your Ubuntu installation exactly the way you want it, and you want to create a live/installer disk image, you can use Pinguy Builder, a fork of Remastersys (which has since been abandoned).
Go to the Pinguy Builder website to get the appropriate version of Pinguy Builder. If you're using Ubuntu 14.04 LTS, then you want version 3.*. If you're using Ubuntu 15.10, use version 4.*.
If you're using Ubuntu 15.10, you'll have to manually download and install xresprobe. You can get the 15.04 version from the Ubuntu packages website, and that will work on 15.10.
The Pinguy Builder website will take you to SourceForge for the download files.
Once you've selected your download, click Save file
After it downloads, double-click it to open it.
The Ubuntu Software Center should launch up. Click Install.
When prompted, type in your password and then click Authenticate.
Wait for Pinguy Builder to install.
Once it's installed, you can close the Ubuntu Software Center.
You should then be able to find Pinguy Builder in a search of the application menus.
Once again, you'll have to authenticate. Then click OK.
If you have other programs still open (e.g., Firefox), close them. Then click OK.
In addition to backing up your system, you may also want to back up a particular user profile to be the default user. If so, click Select next to User, whose current settings will be used as default.
Select the user and then click OK.
To create your backup live/installer disk image, click Dist.
Confirm by clicking OK.
Once the process is done, you'll get a message saying so.
You can then find your .iso in /home/PinguyBuilder/PinguyBuilder. You can burn that as a disk image to a blank DVD or "burn" it to become a bootable USB. Or you can use it to install to a virtual machine.