Looks like quite an engineer to me!!
Make sure you encourage him to keep building things--even if they might seem silly to you. My oldest daughter would always hound me with "Let's build something, Dad!" when she was little. In fact, one of her favorite TV programs was old Norm on PBS building things in his "Yankee Workshop"! She couldn't understand why we couldn't whip up a new dovetailed cedar chest for Mom or an eight floor scale size doll house for her and her sister if we had an hour or two.
Little did she know(at least back then) that Dad was and Iowegian blessed with two left thumbs when it comes to anything beyond basic carpentry. She then got involved in a competition called "Invent Iowa" and won two state titles while she was in Junior High. After the first year she started getting information from Engineering schools in Iowa--after the second, she was contacted by colleges all over the country. It sure didn't hurt her efforts to obtain scholarships, either. Today, she is a pursuing a double major in AG Systems Technology and Marketing at ISU and has started her own little business making jewelry, etc.--its featured on our website under "Barn Bling". I'll be going to ISU the next two weekends to watch her recieve scholarships from the departments she's involved in. In May, we'll see her off for a couple of weeks on an educational trip to Yugoslavia with the ISU Ag and Marketing departments, and as soon as she returns from Europe, we'll be helping her get ready to go to Wyoming for a summer internship with the USDA.
So, like I said, encourage your little engineer!! It seems like only yesterday that I heard "Lets build something, Dad!"