A UFO is an unidentified flying object and as it can’t be identified we don’t know what it is so it would be really hard to build one. Its hard enough building something we can see and touch so I’ve got to admit I wouldn’t like to take on that challenge 🙂
If you wanted to build a UFO from pictures, you could put the images into a computer program and build a 3D model and then print it using a 3D printer…you could very quickly build a large army of identical UFOs! As we dont know how big the aliens are that are flying them, the UFOs could potentially only be centimeters in size…you could make your UFO army in a day!! (and they could be any colour you liked!!)
As I said in my answer to your other question we have never actually found an alien spacecraft which has crash landed on Earth. There are lots of rumours and theories that there have been alien spacecraft found but no real scientific evidence. Although some people believe that scientists have found evidence alien spacecraft and governments are covering it up and keeping it a secret but I don’t believe that myself.
Also a UFO or alien spacecraft is just that Alien or from another world. Why would we want to build one? It wouldn’t be cool or amazing if we had made it would it? I think the idea of alien spacecraft is cool because it proves there is life on another planet, so if we made it is would just be a spacecraft not a UFO. Spacecraft are cool for sure but not as cool as one which came from an alien world!!! That is what I think anyway, how about you? What do you think? 🙂