Let me say right up front that I wasn't aiming to have a completely pose-able "action figure". I am a gamer first. All I really wanted was to be able to swap out weapons quickly and simply. I started out by gluing a pair of 1/32 inch magnets into the upper arm slots at the elbow joint. I shaved down the cowling just a hair to better fit them.
Another thing about this system that I absolutely love is the fact that I can buy additional weapon arms at any time, apply the same magnets, and have a completely new model. In fact, I did just that! I am one additional Assault Cannon and a Cyclone launcher away from fielding the Mortis Pattern Contemptor variant. A simple and shallow hole drilled into the top of the sarcophagus and the Cyclone is also modular.
Stay tuned for pictures of my finished Star Phantom Contemptor with an article discussing the tactical value of the Mortis Pattern.