Can the nailgun upgrade? I know it repairs, but I have NEVER tried upgrading with it. I use the normal claw hammer or, early on, the stone axe.
You added your materials to the nailgun how?
<property name="Allowed_upgrade_items" value="resourceWood,resourceClayLump,resourceSnowBall,resourceScrapIron,resourceForgedIron,resourceForgedSteel,resourceConcreteMix,resourceCobblestones,ironDoorBlockVariantHelper,ironDoorDoubleBlockVariantHelper,vaultDoor01,vaultDoor01Double,ironHatchBlockVariantHelper,vaultHatch01,cellarDoorDoubleIron,cellarDoorDoubleSteel,shuttersIronBlockVariantHelper,shuttersSteelBlockVariantHelper,resourceYuccaFibers,resourceCloth,resourceScrapPolymers,resourceNail"/>
That's the stock line. Did you use something like an "items.xml" file in your mod with the following?
<configs> <set xpath="/items/item[@name='meleeToolRepairT3Nailgun']/property[@name='Allowed_upgrade_items']/@value">resourceWood,resourceClayLump,resourceSnowBall,resourceScrapIron,resourceForgedIron,resourceForgedSteel,resourceConcreteMix,resourceCobblestones,ironDoorBlockVariantHelper,ironDoorDoubleBlockVariantHelper,vaultDoor01,vaultDoor01Double,ironHatchBlockVariantHelper,vaultHatch01,cellarDoorDoubleIron,cellarDoorDoubleSteel,shuttersIronBlockVariantHelper,shuttersSteelBlockVariantHelper,resourceYuccaFibers,resourceCloth,resourceScrapPolymers,resourceNail,resourceForgedMeteoriteRed</set> </configs>
That SHOULD do the trick.