Here is a guide to install Ubuntu Builder on Ubuntu 13.04. You can install Ubuntu Builder by adding the Ubuntu Builder PPA maintaned by Francesco Muriana.
Ubuntu Builder is a simple tool to build your own distribution. It allows to download, extract, customize in many ways and rebuild your ubuntu images. You can customize i386 and amd64 images. Visit the Ubuntu Builder Homepage.
To add the PPA and install Ubuntu Builder open a terminal window (press Ctrl+Alt+T) and copy+paste the following command lines:
sudo add-apt-repository ppa:f-muriana/ubuntu-builder -y
sudo apt-get update && sudo apt-get install ubuntu-builder -y
When Ubuntu Builder is installed you can close the terminal window and to start Ubuntu Builder press the SuperKey and type: ubuntu builder