I thought Calfee's molds were aluminum husks/shells that had a silicone insert in them. By altering the silicone insert, different geometries can be accommodated using one set of aluminum molds.

You might want to read this when it comes to 3D printing with metals
https://3dprintingindustry.com/news/...-part-1-44130/

Spencer is also featured here, with some other links on 3D printed projects at the bottom of the article
3D Printed Titanium Seatmast Topper Coming from Designer Spencer Wright - Bikerumor