My first reaction to seeing these objects was “they look like jointing frames for combining multiple rods”. You’d feed long cylindrical rods into the holes, then use the little knobs to affix them, using them as anchor points for tying the rods into place with string/rope (presumably the rods would have grooves in them to take the rope). Maybe you could make a little tent in this manner, something light, perhaps a bug net for your bed, or something along those lines. Or maybe they were already describing atomic structures 🤓

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Complete nonsense, of course. But that was just my first reaction!