Origami card tutorial: the instructions are not in English, but the pictures are clear enough. I think you can use any size of rectangle paper, but it looks like the paper in the tutorial was skinnier than typical copy paper.
Creating your own DIY gold foil prints is simple! You can turn any laser printed item into a gold foil print at home! Laser printed image, gold foil placed over (gold-side up) and run it through a laminator!