The last pictures you added Tim show typicle ploughed groove American Indian tools, in which the rawhide sits within the groove.
I dont say that means yours are not good, but there very different than the examples you use to illustrate.
When I have time this Ill look through my references on this stuff,looking for similar. I have heaps of stuff on this subject {as you probably would guess,
}but its not been my major focus so far, so sadley cant realy add lib on it.
Spiral