Lowe's has the coolest Craftsman toolboxes on sale.

I bought these to keep in the trailer. I'm going to use Xtrack and straps to hold them in place in front of the trailer. They are waterproof IP56 rated. And they have modules you can add that snap onto each other. The bottom and two other units come as the starter and it is 80.00 and the other modules are between 20 and 40 each. Even the 2 drawer modules have ball bearing sliders.