Minimal Raspbian distribution
Packages that should be installed:
libraspberrypi-bin raspberrypi-bootloader raspi-config
List of packages to remove has been moved to a blog post: Slimming an existing Raspbian install.
Suspect packages that don't appear to be removed…
Building an image from scratch
Buildroot has instructions for an Raspberry Pi target.
https://github.com/debian-pi/raspbian-ua-netinst: Raspbian network installer
Instantly finding a headless Raspberry Pi
Raspberry Pi 2 and Pi 3
Sophisticated debootstrap script, will create an image: https://github.com/drtyhlpr/rpi2-gen-image
Enclosures and mounting
UCTRONICS 19" 3U Raspberry Pi rackmount, w/ 8 mount plates. Can support up to 12 RPi w/ additional plates.