How to create custom Debian Jessie image for Raspberry Pi
Step 1. Dashboard
Dashboard contains a list of all the images you created. Click 'Build New' under 'My Images' to create a new one.
Step 2. Initialization
Select Raspberry Pi 2 or Raspberry Pi 3 under 'Target Device' and 'Debian Jessie' under 'Distro'. Click 'Next' and wait a few seconds while it initializes build environment.
Step 3. Package Management
There are more than 41 000 binary packages from the official Debian repository available. Use 'Search' to navigate through the list. Click + icon to add a package to the image. CusDeb automatically resolves and installs the dependent packages as well.
Please note that CusDeb adds 121 packages to the image. You can't remove these packages.
Step 4. Users & Groups Management
By default the root password for the image is 'cusdeb'. You can change it by clicking on 'root' in the list of system users and groups. Click 'Add User' if you want to create a non-root user account. Once you're done with the users, click 'Next'.
Step 5. Configuration
Specify a preferred language, a timezone and other optional parameters. Once you're done, click 'Build' and wait. Once Build is finished, open Dashboard and download the image.