That's one of mine. The cable is about the gauge of a regular HiFi in-the-box interconnect, same figure-of-8 dual core/screen. I've made cables for ages, so I can't recall where every plug cable came from, but I've stopped shopping at Maplins years ago due to the high prices, these guys do very good prices and free delivery (uk) - i tend to get a bunch of stuff in when i have a few projects to do
I used Neutrik TRS, but the method to attach the screen with those (otherwise top drawer) is fiddly^n - the Rean brand is Neutrik(china) and those particular 1/8 jacks are v good with strong clamps, the little black marker is a bit of sheath from another cable to denote Tip in my studio wiring. I'm pretty sure all of those are readily available, try finding a different TRS though. Some products on that site have pdf diagrams so you can see the config.
If it were me, I'd get some very long stackables, split in two or sacrifice one plug and put two of those in a TRS
For anyone else tuning in there's this route too