You can make a wrench without a workbench. There is a perk for it and it can be made from your inventory now:
<recipe name="meleeToolSalvageT1Wrench" count="1" tags="learnable,perkSalvageOperations">
<ingredient name="resourceForgedIron" count="12"/>
<ingredient name="resourceMechanicalParts" count="4"/>
<ingredient name="resourceDuctTape" count="2"/>
<effect_group>
<passive_effect name="CraftingIngredientCount" level="2,6" operation="perc_add" value=".5,2.5" tags="resourceForgedIron,resourceMechanicalParts,resourceDuctTape"/>
</effect_group>
</recipe>