Do you have a cable that is black with a little red for accent, like about 5% red? My Kinesis is black with 4 (I need 4 more red home row keys) It's bold. A black cable with red accents might just be perfect. Or a red with black (60% red 40% black)?
I don't have any, but I have been looking at some sleeving off of Taobao that matches what you want. I'd have to charge a little more for it due to agent fees and shipping and the lead time will be a couple of weeks, but the quality should be pretty decent to good.
Here's the sleeving I'm referencing:
I could also get some paracord that matches, but I do run the risk of the paracord being too small. Paracord seems to be rather fickle in sizing.
If either of those sounds good to you, let me know and I'll get something going.