Well. For the last product, the GC-3 A1, it took 14 days to be done. But during the time i was doing it, an idea came to my mind:
Doing a futuristic supersonic armed helicopter.

Yes, it may sound impossible because of the way the game limits the prop max speed under supersonic but i'll find a was to do it just fine.

If you want, once done, to see if i made it well, comment T!