There's an electronics tutorial on the wiki in the element usage tutorials section that is very helpful for figuring out logic gates and such, Zuev.

Essentially, PTCT and NTCT, in conjunction with METL, NSCN and PSCN, are the key materials for producing logic gates of a very compact and small nature. You could kind of achieve logic gates with SWCH, I think, but it's easier with the aforementioned elements.

As you may or may not know, PTCT and NTCT are elements that have temperature dependent conductivity, which you can manipulate with METL. Experiment with them a bit. But essentially, use METL to manipulate the temperature of NTCT or PTCT and use PSCN and / or NSCN to transfer electricity over to and from the PTCT or NTCT, if that makes any sense.