If you click the map image above it will provide you an easy to use Map of All Locked Toolboxes. The toolboxes contain various items from plans to scrap and ammo. You can also click this link to see the map too.
While searching you just might find the plan to create your own toolbox to display in your C.A.M.P. Here is an image of the stash boxes you can use. You might also want to check out the Locked Safes locations that are throughout the wasteland.
Where to find the Ingredients for Cranberry Relish - Map
Where to find/farm Stingwings in Fallout 76?
Where to find/farm Firefly Locations in Fallout 76?
Where to find/farm Oil in Fallout 76
Where to get the Water Well in Fallout 76?
Where to find/locate Super Mutants in Fallout 76?
Where to find Asylum Worker Uniforms / Apparel in Fallout 76
Where to Find a Shovel in Fallout 76?