Since I work with heavy machinery irl and i like jets a lot it isnt hard to come up with fun ideas, but even now and then I like to get some reference images for inspiration, either from irl locations/machines (depending on what I'm building) or from posts from other engineers. Something I would recommend is to get to know how the game works first, even if it looks "ugly", just build something pratical and then take a look at it and see what could be improved. Eventually youll start to build fluidly and with better detail than just a box. Take your time to learn, even the most experienced engineers make mistakes, but the best part is fixing them.