You can get rid of the yellowing by soaking the shell of the NES is dilute hydrogen peroxide and shining UV lights on the shell. There's a bunch of tutorials all around.

https://amaiorano.io/2022/09/13/nes-restoration.html#retrobriting

[–] CptEnder@lemmy.world 3 points 2 weeks ago (1 children)

Would this work for LEGO as well? One of my sets started yellowing because it gets too much sunlight

[–] Console_Modder@sh.itjust.works 4 points 2 weeks ago

I think so. After some quick googling, it looks like some people get it to work on white, grey, and blue bricks, but leaving it in too long causes white "chalky" spots to form. Try at your own risk I guess