Cut a mild steel tube, I used square 3x3x6 inches. seal one end, cut cable to fit in the tube. Stuff as much as possible into the tube, I have even used my press to push it in. Then I shake powder into the "can" until it won't take any more and then pack it in with my press to get in a bit more. give a shot of WD40 and seal the other end. I drill a small pressure release hole into the side to prevent the pressure from splitting the can. Then bring it up to welding temp and squish it. Once you have it packed good so the press is working hard and it is now solid, then grind off the can. Makes for a nice clean cable billet. Very few inclusions or cold shuts. I do clean the cable by burning it out and wire brushing each bundle.
This was a readers digest version. but thats how i do it.
Chuck