Minimal Ubuntu GNOME Custom ISO

I need a custom Ubuntu ISO built from scratch with a minimal GNOME desktop. The environment should be lightweight and secure, with no additional software pre-installed.

Requirements include:
- SECDNS integration
- Custom firewall setup
- No file shares or remote access
- Basic light browsing functionalities only

Ideal skills and experience:
- Expertise in building custom Linux distros, particularly Ubuntu
- Proficiency in GNOME desktop customization
- Strong knowledge of security configurations and firewall setups
- Experience in creating minimal, lightweight ISOs