Where to Find the Crafting Tool
The Crafting Tool can be found towards the beginning of the game when Lara goes with Jacob into the abandoned mines as a shortcut to get to his village in the Geothermal valley. It isn’t particularly well-hidden, either. Probably because of how important the crafting tools are in Rise of the Tomb Raider.
Simply progress through until you reach the ice cavern with the trucks hanging off the ledge and the big door across the chasm. When you reach that room, there will be a handful of enemies for you to take out. No big deal, do what you do best. Then, simply walk over to the strongbox in the left side of the room (pictured above) and claim the Crafting Tool. The crafting tool will unlock the first extra set of weapon upgrades in Rise of the Tomb Raider.