3D Modeling software for 13 year old

I bought my nephew an A1 and he absolutely loves it. I barely had to teach him anything as he figured everything out through youtube videos. The kid is smart and on his way to becoming an engineer one day.

Whats a good modeling software that's easy to use and learn for kids so he can model stuff himself?

I currently use solidworks but that is way to complicated for a kid to learn. Only reason I use solidworks is because I use it every day at work and am familiar with it.

What are your thoughts on which software to get him into?