I'm looking for ideas for my brothers to get something for my sons (2 and 4) for Xmas. Ds1 loves building ships/rockets/submarines/castles etc out of building blocks but we don't have any construction stuff, not even Lego. I'd like something where he can really use his imagination for creating engines and machinery as he's fascinated by them. Should I get Lego or look at Playmobil or is there something else? Anything aged 5 and up would probably be ok as his brother doesn't necessarily have to share it yet.