Here is the Poser box primitive, exported as obj, then imported twice with the "weld identical vertices" option turned on.

Both have smoothing turned on. The upper one has crease angle 100, the lower crease angle was 80. Since the edges are 90 degrees, the lower one is all crease no smoothing, the upper one is all smooth, no crease. Objects with various angles would have various parts smooth or creased as specified.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)