It depends on how much of the build you want to do. The easiest way i have found is to use Adsb.im, which installs relatively simply using the rpi build and then gives a gui to setup multple feeders.
Recently Tristan said in this link that Safesky receives from adsbhub.org and adsb.fi so settjng those as a minimum will help.
My current home setup has adsbexchange installed as a base, and then i have added other feeders from the command line.