Kudos to your niece, that is some impressive work. I'm sure your boy will love it.
Our niece is also a talented baker. She actually made our wedding and bridegroom cakes for us and did a fine job. My mom was visiting us last month, and while here, she had her birthday. She is a big flower grower, and especially loves her hydrangeas. My wife saw a cool video on Facebook about making cakes that look like hydrangeas, and forwarded to our niece and asked if she could pull it off. She said she probably could. My wife helped with some of it, but the niece did most of the work.
Anyways, here are the results. Everyone thought she did an great job. And the taste was awesome. The cake also had different colored layers. Mom was delighted by it, and thought the taste was delicious.