I had an old Strombecker that needed new braids. As I was rummaging through my parts box, I came across some extra Scalextric guide flags.
I tried one braid, and it was almost a perfect fit:
To get the length right I folded-over one end:
This seemed to work great:
But don't do it. When I tried to insert the motor wire, it was too tight of a fit and I had to unfold it.
But I'm happy to report that the new braids look and work great:
Ron