So I'm considering the feasibility of casting these in either investment or shell using al-bronze. Ideally with the hex hole in place, can be broached clean afterwards. The other holes can be machined post clean up. I can use the originals as patterns and the minor shrinkage should't be an issue. I would hope to cast 6 or more per mould to be economic. Any ideas how much shrinkage I can expect with al-bronze, any pointers or suggestions? I'm not geared up for either process yet, just chunking around ideas.