Why do you want to build one, just to prove you can solder? You will have enough problems. Just buy something simple like a bare bones UNO for $5 and then buy some stuff to go with it. I would never suggest the kits that supply a bunch of stuff that will never be used. Micros are like children. Each of them are different, but they are all the same. You will never figure out what to use till you find out what you don't like.