Prerequisites

What do you need to have?

First of all you need a server: i will assume you have a system that will be powered on 24/7 and will be accessible via network, be it your home network and/or an external network. There are many options for this, which could be summarized as:

  A NAS or simial option (TrueNAS, Synology, etc...)
  A brand-new server
  A Pi or similar small factor thingy with a networked drive
  Recycle some old hardware you have around

I will always be referring to a server on which you will install Gentoo (which rules out NAS-like options, since they have proprietary OS usually).

Personally, i go with recycling hardware. I had an oldish laptop with a broken down keyboard, low wattage and very quiet, the perfect option for me. To give you a quick hardware tour: Asus thin laptop with Intel i5 CPU, 8GB RAM, 256GB internal SSD for Gentoo installation, one wired ethernet gigabit and three nice USB3 ports.