The wire I purchase I do so at 15,000 feet at a time from a major manufacturer, ofc, 24 awg. I did not say it was essentially the same wire in those exact words; it is probably larger than some Mogami used and the strand count could well be different, I just said if I want to buy individual wire, I tend to do just that. Most anyone can approach Mogami, Belden, Canare, Carol, etc and offer to buy specific types of wire but there are usually minimum purchases required, or even special runs of wire. They will brand it any way you like, if you purchase enough but the normal DIYer does not generally need those quantities.
While cloth, paper, and string stuff are not exactly great conductors, I was unaware they were being used as dielectric materials in star quad but I guess the term could apply. I have heard of such things referred to as fillers. Fillers are used to keep the cable round and to eliminate convolution.