Oooh... that'd be dangerous. The rubber idea's a good one.

Thanks, I assume something light rubber they tightened around your hands. Like a slap bracket but much stronger lol!

"Modern problems require modern solutions." -slap bracelet, 2022

Metal cuffs should still work. Shooting your cuffs with lightning is more dangerous to you than anyone else, and not everyone can generate lightning while their hands are restricted. Other things that have been used to restrain lightningbenders are ropes, chains, a straightjacket and nothing at all besides the prison cell. Most of the time, these are also combined with people keeping watch over you, so if you tried to escape, you'd have to fight them while at a serious disadvantage. It should be possible for firebenders to break out of ropes because zuko burned through a banner aang tried to restrain him with in the 2nd episode, but maybe not everyone can do it

^Surely a lightning bender could control the lightning being conducted through the metal tho

Nah. Firebenders seem to have no control of the lightning once it leaves their fingers.