I've seen a few people struggling with this lately, particularly where they are putting a bend in a joint. Here is the way to do it so your not guessing as to how much your changing the length of whatever your working with. This is a set of semi-sneak forms that I am altering for a locked set that I am doing. This set was locked so that they do come apart when the skull plates are removed from the forms. Both forms will need to turn more than they are and rotate some in the necks/heads e You want to determine the center line or pivot point for whatever joint you are altering. In this case the vertebrae are the pivot point for this joint. You want to cut wedges out of the side you want to turn towards up to your pivot point, then cut straight through the opposite side. This allows the inside of your turn to close up and the outside to open up like it would naturally. Once I cut the sections apart I place a wire through the center of the joint, in this case again where the vertebrae would be. In this case I ran two wires so the heads wouldn't rotate with the antlers attached. It took me less than an hour by myself to lock these deer up. All I do after this is wrap the necks in garbage bags and pour foam down the joints. Once it's set you just carve it down and blend the seams together. I will have less than two hours in alterations for this set of locked deer.