"I've already had some luck with the Smeargles, so the world itself shouldn't be much harder." Granted, the Void wouldn't be able to provide feedback confirming that it understood, at least not for a while, so there's that complication to deal with... but still, he's pretty confident he can do it. And maybe once it understands writing, teaching it other things will be easier, too.

"Wouldn't it be more useful for you?" Kaiba is some kind of engineer, right? "I've already got one, anyway." He pulls a small pocket knife from his labcoat, unfolding it to show the handful of tools on it. "If you don't have one already, you can have that one." How generous.

((BTW, up to you if you want Kaiba to succeed in rebuilding the chair or not! It might be an unhealthy boost to his ego if he succeeds, but then again, it would also be pretty funny....))