Our team did a forklift last year. It worked very well, though it did have a habit of jamming when going down. We used 80/20 and those wheels that run up the side in order to make it.
In order to counteract the balance issue, we put both motors in the back, using chains to maintain front wheel drive (thus making it extremely easy to control), and also putting the battery in the back.
One thing that was a problem last year was that (at my suggestion
) we attempted to make the forklift able to fall, allowing teams more room to ride up on our ramps. This destabilized the forklift to a great degree and made us spend the last few days rectifying the mistake. In short: don't do anything fancy with your forklift.