This is a sub-topic fork of @alzer89's Automated Qubes OS Installation using Kickstart and/or PXE Network Boot, focused on creating a repeatable guide to PXE Network Boot a RAM-based Qubes OS.
Basic concept: Your Qubes OS installation sits on another computer with the PXE server software. You can then have as many client computers as you want PXE network boot from this RAM-based Qubes OS using only their network connection and no drives needed to boot from. Your client computers reboot to a 100% clean Qubes OS state each time. Scales to many client computers at once.
RAM-based Qubes OS over PXE Network Boot is very useful for:
Running further stateless endpoint computers without storage drives in them.
Anti-forensics. Nothing stored on endpoint computers, except firmware of the hardware parts. No drives necessary at all.
Disposable Qubes OS. Just easily reboot to instantly make and boot a new clean install of Qubes OS many times per day.
Quick centralized management & deployment of Qubes OS configurations/updates to multiple endpoint computers.
Interesting initial conversations and a general Qubes OS PXE installer implementation in the general topic thread mentioned above.
Note: If you'd alternatively just like to run a RAM-based Qubes OS from a normal boot drive, then this is already available using @xuy's Qubes in tmpfs.