3 pair of scrap knuckles can be crafted with the following recipes

Autolearned
Player Recipe
Primary skill used: fabrication(2)
Required skills: bashing(1)
Time to complete: 30 minutes
Tools required:
> 1 tool with hammering quality of 1
> 1 tool with metal sawing quality of 1
Components required:
> 4x rag
> 4x scrap metal
Byproducts:
(none)