Heat-Pop Method: There are a couple ways to go about this: you can boil the figure, or use a hair dryer/heat gun. A heat gun is something more experienced customizers use, mostly because it's very easy to melt plastic with them. So stick with a hair dryer. It's fast, and safe! All you need to do is wave the dryer three to four inches away from the parts you're taking apart. The plastic will become soft fairly fast, and you can just pull or bend the pieces apart. You need to use a small screwdriver to push those hard plastic pegs out of larger figures though.

Cracking Bodies Open: Don't do this unless you're retrieving parts, such as shoulders or ball hips. Most bodies that we've cracked apart were destroyed in doing so. We've been lucky a few times, but it's up to your Discretion. All you have to do is pop the head off, stick some closed needle nose pliers in there, and open them up. That usually pops the body in half with no trouble and this works on a lot of Legends, but not all. Some figures you need to boil, and pop using a screwdriver; and some just need to be sawed open. It just depends.

Heads are rolling: So you want to add that Agent Scully head to that Mystique body.. Ok, aside from the fact that it's way too small, she's got that giant neck to deal with. If you look at your current Marvel Legends female heads, or any head, you'll notice that they all have a clean jaw and skull line. You're going to want to cut that neck out, and bore out the head with dremel bit #114, so the peg will fit proper.

To attach the head, use a little hot glue, or apoxie sculpt. Just make sure to turn the head so that it does not set up in one position. If that happens, then you'll just have to pop it off and start over, or have severe neck injury hero-guy.