If you don't mind stripping it. (I mean I strip everything I consider useless because it's part of my routine for a long time. I don't look for scrap. It just comes... I'm an electrician!)
Do whatever makes you happy. I recommend making a cheap spring loaded utility knife into a slot perfectly aligned with a hole sized for the wire.
You'll first have to strip the outer jacket with some kind of sharpened up romex casing glide stripper, or squeeze it just right between two long boards using clamps you'll have to keep hoping over as you cut with a knife like dissecting a frog. might take you 2 hours to get them all stripped if you focus. Then the 3 insulated wires will need to get pulled through that simple rig with the razor blade. (drill a hole through it to put a long bolt between two upright boards screwed to a block then attach an extension spring from the top end of the utility-knife handle, pull it enough to have sufficient tension and drill your second bolt there in front of the blade tilting away from you. As the spring pulls on the back it drives the blade down into the slot. You have to first make the slot, then carefully drill the hole to where the tip of the blade can go 60% into the hole path. (a drill press is best) Now fasten the rig to a table or sturdy wall... and feed the wire from the back side away from the spring and blade so it is being pulled through the blade.
You could design a block with multiple slots and sized holes for each kind of wire you encounter and the blade can easily slide when you push it to stretch the spring more, lifting the blade out of the slot.
This would be a low cost efficient way for you to strip the stuff. It will add up. store it in a vacuum bag and tear it open the day you decide to take it all in. (1000 lbs or more and refined, and you can negotiate way better rates). I called them up the other day before taking in 5 tons of purity tested bare bright copper. try to guess how much cash I walked out with and then tell me who the scrap yard is going to sell it to. Betchya can't!
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