Wiktionary
preshape
vb. (context transitive English) To shape in advance.
Usage examples of "preshape".
As she began to preshape the flint in the Clan way, and the Mamutoi flint knappers realized what she was doing, they were eager to watch, and crowded as close as they dared.
They are not without skill, but it's a long step from preshaping a core to an intermediary punch, and that makes the difference between a heavy flake tool and a fine, light blade tool.
Since he was all set up for shaping wood, he decided make some new spears, to replace those that had been lost or broken Wymez had given him some good flint before he left, roughed a and preshaped so that new points could be made easily.