I dug up a 2-year old crabapple in my backyard and transplanted it into a training pot that's about 6-7 inches deep. In the ground, this sapling was over 6.5 feet tall. I trunk chopped it above the twin trunks. The root ball is about 6 inches in diameter. I cut off any roots that were thicker than 2-3 mm in diameter, keeping the finer roots intact. I hope this takes root and begins growing this spring. Otherwise, this will be the 3rd bonsai I've killed ;-)

Anyway, I'll keep you posted and I'll post a picture when I have a chance.