sleek:
Cool idea and worth testing. Most new ideas don't work, but so what. When used as a bow string it has a lot of stretch, so might have high hysteresis. Easy enough to find out. Horse tail might be the easiest, being so coarse. Hide glue might not like sticking to it. Maybe test that separately. When ready for the belly test maybe glue up thin bundles, as if preparing sinew for backing, letting each fully dry before setting in place and pouring glue on. This will way speed belly drying time, and reduce shrinkage,