If you have screenshots from other games, and images from the real world, sure. Do whatever you want to do, even the things I 'hate'. It's your game so do enjoy it
You'll however have to get cotton to turn to cloth (loom) put into the paper press, press it, bucket it, press it, grab it, then turn it into posters. You can make a good few stacks of paper within an hour.
Thank you!