Those look good!
I have messed around with hinges a bit. The clamp I made is sort of similar, although I used metal dowel pins for strength.
I would go witht he wooden dowels, although you can make the cut circles work if you want to.
My suggestions:
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Put in alignment holes so that when you glue the circles back on you can stick a nail or something through the whole assembly and line up both sides perfectly.
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Sand the outside of the circles and the inside of the holes a little bit to get rid of the tiny ridges left by cutting.
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When you glue on the circles you need to try very hard not to squeeze glue out onto the surface around them. Try engraving a fine line just a hair larger then the circle to trap any squeeze out.
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The inside layers of most plywood are not very hard (they use the hardwood on the outside and softer wood inside), so they will wear out pretty quickly.
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Use dowels instead, but measure each one so you don’t get stuck by varying diameters.
Most wood dowels are not vey precisely manufactured…