I don't fully understand the question. If you are asking where to buy wire to thru-wire plugs then I have an answer. I have always (10+ years) used stainless welding rod in 306 hardness. It is a little hard to bend so I bought a box of it (about 25#) and had it heat treated) Now it bends easy without loosing any of it tensile strength or stainless properties.
The other guys may have other ways of doing it.
Where can you buy the stock to place in the wire bender fo use in through wiring?
Swimmer a.k.a. YO YO MA
Serial Mailbox Killer/Seal Fisherman