As it turns out, there's always another kumihimo necklace.
The back is smooth, and every three inches or so, I use a slightly bigger/more sticky-out (that's a technical term) bead on one of the threads and there are three sizes of sticky-out, so by the time I reached centre front I realized that this was a pretty long one but the thread I cut was the same as for a necklace six inches shorter, though I tend to have waste.
As I neared the finish, a couple of the threads were too short to be securely wrapped around the bobbins, so I tied a great big honking knot at the end of the thread (to prevent fall-offage of beads) and I finished with no more than an inch or two to spare.
Yeah! Livin' dangerously!