Lenses for VR-cardboard: what to take, what is the safe distance for the eyes?

Question

Do it yourself

Maybe the question is from the category of superstitions - I am not friends with physics, optics. How to choose lenses? And what distance should be between the eyes and the lenses and the lenses and the screen (there are a lot of photos on Google with homemade helmets of various "lengths")?

Answer 1

> What parameters to choose lenses?
By focal length live!
> I'm not friends with optics,
take pink ones!!

Answer 2

Google 's website has all the specs.