3-Ds can be humbling, but they are great learning experiences for hunting situations. Good practice for 3-Ds is shooting tennis balls with judos in an open field. Throw out two or three tennis balls, where they stop is where they get shot at. One shot per person at each ball. If a ball gets hit, the next shot in the group is taken from where the ball stops rolling. When you get to where you are hitting 8 of 10 at varied ranges you are on your game. A definate "Pick a Spot" exercise and alot of fun. You can do this by your self but it is 10 times more fun in a group of two or three.