Gift for a boy

My spouse is going to start having his kids stay at my house on his weekends. I have no kids and two extra bedrooms so they each get their own. I want them to feel excited to come here so I wanted to get them each a special present for their rooms. I got his daughter a vanity that I'm refurbishing.

He has a 7-year-old son and I can't figure out what to get him for his room. Any suggestion

UPDATE: FINISHED PROJECT***