I found the 6x8 plate was necessary to strengthen the door - the bottom of these soccer squares doesn't grip very well - I had tried a 6x6 plate (which works well enough for the top of the hinge) but the bottom of the soccer piece only connects with 4 studs on the plate.
The hinge mechanism is a little more bulky then I'd like, but it was the smallest way I could get it to work with enough strength. Please let me know if you improve on this!
The way the droid arms connect for the hinge means the door is offset about a 1/4 stud from the rest of the cube - this is perfect, as it allows for some extra friction when you close the door - you can hold the pod with the door down, and it won't fall open.
Also, I put a green 1x2 plate in the spot on the roof right above the door, so you can hold the door in an open position. If you push down and rock the door closed, the plate will stay on the roof, instead of coming off with the door. Hope that makes sense :)
Feel free to email me if the pictures aren't explanation enough, I'll update this page to answer any questions.