Thinner the better. It'll make it alot more durable, but rod cast a good bit. It doesn't return as fst sa thinner rawhide or sinew. Or paper bags for that matter
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Seems that it's better left for grips and what not. Butcher paper, brown grocery bags, and strips of old sheets all have worked well for me in "tests" bows. Sheets were the easiest to get a full lenght piece- but the papers were the easiest to paint on.