A room, space, corner or area of a dwelling that is specifically reserved for a male person to be in a solitary condition, away from the rest of the household in order to work, play, involve himself in certain hobbies, activities without interuption. This area is usually decorated by the male that uses it without interferance from any female influence. (urban dictionary)
Connor wanted to share his creation the second it was complete. He worked 3 days on it (off and on and would have stayed out there 24/7 if I'd have let him) and he's very proud of it, although he did mention he wished he could have used a jack hammer to whittle a tunnel under the street. He is already talking about building an addition to it. The sled is a door or an escape route according to his master plans. The first thing that came to my mind when I saw it was "man cave". Made me smile. All boy.