r/cakedecorating

So on The Great British Bake Off, they're always making mad structures out of tempered chocolate, and now I've got an idea for a cake that would need a fairly simple object constructing out of it, but I have no idea how you go about making the moulds.

It's a cake for a 70th, and the request is to have the top of the cake decorated with tools (he's a very practical man and is proud of his shed and tool collection). I thought it'd be cool to have a toolbox full of tools on top, and I've found chocolate tools I can just buy, but it's the toolbox I'd like to try building out of tempered chocolate - imagine a simple wooden toolbox. How much work would it be to make, and what advice could you give?