Nuts n' bolts are a common resource. You typically find them when breaking open metallic objects. There are lots of metal objects you can break for nuts n' bolts, like cars, refrigerators, arcade machines, playground equipment, small metal cans (always on the far edges of the map). All of these metal objects will normally give you nuts n' bolts. The metal cans will always drop nuts n' bolts, but there is only a high chance with the rest. Metallic objects are also limited. To get nuts n' bolts more quickly and easily, unlock Map 2: Plankerton. Get the "Repair The Shelter" quest. Uncover areas of the map to reveal yellow dots. The yellow dots are cache locations. Loot them to get 75+ nuts n' bolts per cache. The more area you uncover on the map, the more caches you can collect for easy nuts n' bolts.