A ruined portal is a naturally generated damaged nether portal, which spawns in both the Nether and the Overworld. It contains some decoration and a loot chest around it. - Minecraft Gamepedia
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Print the second page (The one with the crying obsidian) 1 time, and then just print the third page (the one with a 2x1 obsidian block) 3 times.
M16 who helped me so much by fixing the scaling errors in the design.
Also see my Mini Ruined Portal
1. Click on the papercraft design image.
2. Make sure it has not been resized by your browser (you might need to click the image again).
3. Print using your browser's Print function.