/ entrenching tool can be crafted with the following recipes

Autolearned
Player Recipe
Primary skill used: fabrication(7)
Required skills: N/A
Time to complete: 300 minutes
Tools required:
> 1 tool with grinding quality of 2
> 1 tool with anvil quality of 3
> 1 tool with hammering quality of 3
> hotcut
> electric forge (320 charges) OR acetylene torch (320 charges) OR electric arc furnace (160 charges) OR charcoal forge (320 charges) OR basecamp forge (320 charges) OR demon forge (320 charges) OR rock forge (320 charges)
> metal fileset OR pair of flatjaw tongs
Components required:
> 4x lump of steel OR 16x chunk of steel OR 80x scrap metal
Byproducts:
(none)
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This recipe can be found in the following books when fabrication is at least the required level:
101 Crafts for Beginners (level 3)
DIY Compendium (level 4)