I'm not sure what the fascination is with aliens but they can be fun to imagine! I love the green aliens from Toy Story ;)
I LOVE this Alien and spaceship craft from ikat bag. Especially because you can play with it afterwards!
This little guy is super cute too and may be easier for younger ones from A Little Delightful
If it's just the aliens you're after you can craft some up with pipe cleaners just like Craft Jr.