I was thinking about how they did the hollow part. The mold needs a carefully centered stopper where the shaft goes. Some sort of jig of wires to keep it in place.
There's index hole on the bottom, you can see it running across.
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Stone Moulds from Terramare (Northern Italy): Analytical Approach and Experimental Reproduction
Persistent Identifier
https://exarc.net/ark:/88735/10145
Fig 11. Ophiolite multiple mould for razor and spear-head.
