Even for that part there is no real difficult steps, even if you have never done electronics like me before.
But you don't have to if you choosed the "No Soldering" kit option like I did.
That said, the documentation for building these parts is very poor compared to the very detailed instructions provided for the build of the machine structure itself.

I can say that the kit is now completely built so I should be able to try my machine.
All in all, I think it took me about 18-20 hours to finish it.
But if I had to build another one, I'm sure I could go much faster, saving let's say...maybe 4 hours ?

The overall look of my finished machine is just great !
(there is allready some customization on this photo because as an asshole I didn't take any when I just finished building it) 

Now let's try it...