The Tiger had a metal box containing tools. Earlier versions of Tiger kept it on the outside rear wall.
This is a toolbox on the rear of a Tiger. It sits in a metal tray. As I point out, there are four clasps ranged along its front; two of them close the box' lid, and the other two are on straps that hold the box in the tray. The box also has a lock.
These clasps are all identical. They are a standard German item that is found on all sorts of equipment. Images are very easy to find.
Here is the toolbox provided in Border's kit. It doesn't have the smooth rounded form of the real box. It has clasps molded in, but they are about twice the length that they should be.
Border have neglected to give this part a number. It can be found on the "Z" sprue.