I'm an 80s kid and we passionately played conkers at my primary school. We used to hang them on shoe laces or string, by burning a hole through the middle with a heated awl or kebab rod.

Cheating was always rife with people using all manner of techniques to try to preserve and strengthen their conkers: soaking in vinegar, baking them, coating in nail varnish, &c.

Pretty sad to hear it's fallen out of fashion, as it was good, cheap fun and, with long enough string, not very dangerous.