Don't cut corners, just pick up some 10/3 at Lowe's Depot and do it the right way. And don't cut corners on wire (which means any hot/neutral wires must be insulated and the bare copper wire is for grounding purposes only, I've heard news stories of kids being fried because an electrician cut corners and used the bare copper wire on 14/2 for a traveler wire on a three way switch instead of 14/3).
Do it right, don't cut corners. Having a kid or another loved one (or yourself) getting electrocuted is not worth saving $10 on wire. Get the right wire for the job. If you don't know how to or want to do it the right way, call a reputable electrician.
The incident involving the electrocuted kid, the electrician did not even pull the permits so it was never inspected.