A lathe and a mill would be very helpful but barring those: A belt sander, a bench grinder, another bench grinder for buffing, a band saw would be handy, a drill press, a good vise for said press, parallel bars (not the gymnastic kind
), an arbor press, if you are going to build AKs then a hydraulic press, a bench vise or two with the appropriate soft jaws, an air compressor, specialty tools like AR barrel wrenches and such, an oxy-acetalene rig or at least a MAP torch, TiG welder, assorted punches and hammers, a bench block or two, more screwdrivers than any human being should own (those hollow ground bit sets are great but you will need some that you don't mind grinding on or bending), files of all shapes and sizes, a file card to clean them, and last but not least a place to put all of this mess.