The Tool Box is a portable storage item from IndustrialCraft2. When closed (looks like tools are spilling out of it in the default image) it can be right clicked to "open" it.
When opened, it will release the tools it contains into your hotbar or inventory. If you close it (right click while holding) it will take in all the tools in your hotbar for storage until opened again.
If you put tools in your tool box then put items in the places the tools used to be, the tools will spill out on to the ground if you right-click the tool box.