Many very complex tools.
You need a design for a helicopter. That design will tell you what materials you need...because every heli has different materials in it. The things you need to build a Robinson R-22 are different from the things you need to build a Sikorsky CH-53E.
all different tools
The cheapest way to build a helicopter is to build a LOT of them. This way you get economies of scale.
wood or strals
To build that bookcase, you need the proper tools for the job.
You need many power tools to build a house as well as basic tools like tape measures, hammers and saws. Depending on what kind of work is going into the house will also depend on the type of tools you use.
* iron * wood * tools * wire
Tools are important to engineers because they need it to help build, repair or make things if they didn't have it. If they didn't have tools, it would be impossible for them to make a repair or build so it is very important for them to have tools.
You will need some special tools. You will need to have some stone cutting tools in order to create your stone garden benches.
That depends on what level your talking about in the level of Cat woman you will have to build it and in other levels you either have to build it or build a thing you have to push and get the helicopter out of a shed or something.
Igor never flew a helicopter, but he did build one though.
He didn't have or build an actual helicopter. It was just a sketch.