I always seem to get a lot of warp when gluing sheets together with wood glue. Same with sticks but I use CA to glue sticks together so they don't warp. I just gave contact cement a try on my last build and it worked out pretty good. I used a hard roller to get it on both halves, let it set up then put the two sides together.
Be warned, when you touch those two sides together they stick!! Like right away!! I used my building board to make sure the edges were straight then put them together. Still got a warp though, just not as bad as when I use wood glue.