Learn how to create custom Ubuntu and Debian container base images using simple tools like debootstrap and multistrap. Explore the process of building root filesystems tailored to your needs, gaining a deeper understanding of container construction and debugging. Discover techniques to avoid common pitfalls and optimize your builds and testing procedures. Through worked examples, master the creation of bootable root filesystems and explore options for immediate use, improvements, and simple booting methods. Gain insights into building VM disk images and leveraging libvirt and LXC for container management.