While running my construction business I used a WEATHER GUARD Truck Box to maintain small tools for my crews. Stuff like razor blade replacement blades, tape measures, trowels, sponges, and parts for tile cutters, in addition to having a set of tools that were my own.
That box was tough and watertight. It was lockable with a dependable mechanism. It’s aluminum diamond plate finish looked good on my black F250 XLT.
These are a premium box and cost more than those basic tool boxes you’ll find at the big box stores, but the quality makes them very worthwhile. These are sold at Home Depot and Amazon, Tractor Supply, not to mention many other locations. Recommended!