I disliked that Menasor's combined mode arms were not stable enough to stay in place. Before Perfect Effect had come out with their kit, I had already designed this for my figure. Both vents slide over Motormaster's arms and lock them in place. A small tab along the front, let's the combined forms head to slide over and keep the head from moving about. On the back I put two 5mm holes for weapon storage. I tried to make the vents look a little G1ish. *Update*: was taken off being printable or sellable, but that was because my printer's extruder was clogged up. And that made the prints wispy and not very unstable. Which made me think their was a error in my design.