Hello, I did some origami with a japanese thin newspaper but Id like it to be more sustained and have like a harder finishing.
What do you suggest to do to harden them? Some product maybe?

you could try using modge podge spray to harden it or maybe resin

You can try resin or transparent glue, but I'm not sure if this is considered "glitching the game", you could try the next time to use two copies of the same newspaper page and sandwich them with a blank paper in the middle