The Proteus non-cuttable bar uses ceramic spheres in a cellular aluminum structure to dull cutting tools.
https://s3-us-west-1.amazonaws.com/h...ttable_bar.jpg
https://s3-us-west-1.amazonaws.com/h...table_bar1.jpg
More:
https://newatlas.com/materials/prote...ke-lock-armor/
Originally posted by FEM2008. Reposted with larger images.