Gentoo Linux is a source based distribution - which means you compile everything yourself. It's also called a meta distribution because it's fairly easy to roll your own distro based off of it. That is exactly what I've done for my current iteration of my virtual machine image. On this server ( hosted by contabo ) I've got a chroot set up with a current x86_64 gentoo installation. Every night a new virtual machine image is built from this.
Below this post you can find the current virtual machine images I'm using - and an image for an USB stick ( minimum 8GB recommended ). These virtual machine images ( or the compiled kernel ) will automatically pull a current root filesystem from this website, then boot into a working linux environment.
These images support VirtualBox, Microsoft Hyper-V and KVM virtual machines. They will also work on most laptops. I've included an automatic X configuration script ( which you can disable by typing "rc-update del xconfig default" ) as well as a NVIDIA prime GPU switcher for use with a laptop. There's also a gzipped disk image that can be written to an USB stick contained in the post below. On windows this can be written to an USB stick using Win32 disk imager
The second partition of the image will - on boot be resized to match the disk size of the USB stick you use. If your USB stick is smaller than 8G in size or a second partition does not exist booting from the network will be attempted using any *wired* network card. If for any reason your filesystem is damaged network boot will also be attempted.
On first startup the USB stick or Virtual machine will attempt to fetch a current image from the server - for this it requires a *wired* ethernet connection. Updating can also be done via the same connection.
You can also find the script used to build the images below.
Update ( 11 aug 2020 ): I've added R-studio for data mining purposes. There was a bug in squashfs with bigger block sizes where on multi-core systems squashfs was unable to retrieve blocks correctly. For now I've settled for a slightly larger system image - but I will experiment with different block sizes more in the future.