At 3 years 8 months & 3 weeks’ old, X built a proper Lego model on his own by referring to the instructions.
It was an easy-to-build set meant for 4 to 7 years’ old. He was so bent on completing it that he covered all 3 packets from the car to the lab and prison in one night.
We helped him when he had difficulties assembling some of the trickier pieces together and also rectified his minor mistakes.
All in all, we were impressed with his output.