There are plenty of cool projects you can try with LEGO. ajw61185’s giant LEGO helicopter is also pretty neat. It is based on the helicopter from 6396 International Jetport. The challenge was to keep the weight down. As the maker explains, the helicopter is made sheet EPS covered with 3mm depron foam. It is powered by a 4s4000mAh battery.
A naze32 is used for flight control. More info is available here.