Thanks...he is loving sharing his builds. He also did creepiest herobrine that i posted on here too. If your son is building at close to 4 then he must have a high iq. My son loves minecraft and has been playing since he was 4 and a half at pocket edition. He built this in a few minutes though so it wasn't much effort. You will be amazed at how fast your son will be in 2 years.
I saw his other one too. My son will be four in three months. Right now he builds small square structures and you're right, they learn fast. He couldn't do that a month ago. He loves blowing things up with TNT that I build also. Lol.