He gives Steve a look which results in the other man holding both hands up, then shakes his head, chuckling a bit, and turns back to Sharon and the tower. Bucky considers it for a moment, then eases the next block free. He flips it over in his fingers, considering.

"I'm more used to breaking things down than building them up," he observes, and sets the block carefully on the edge. "But I guess it's really just doing it in reverse."