To make a moveable OPD you can consider adding skeletions inside the body to make it move. Skeletons can be wire armature or loc-lines. However, to make the OPD moves, it's a tricky process - you got to trial and error on your first few designs to study the amount of tolerance space needed for the skeleton to move.
Right now for this case, I am experimenting on a little pup this week. Yesterday night I have finish sewing the whole body and flipped it inside out. Looking at the amount of space in between the legs, I think an armature might not work at all. I hope he can be completed this week and I'll share with you later.
|Side view of the pup before turning|
|This is his frontal view, looks ugly isn't it? :p|
|Ah... looking good after turning. He is not stuffed yet!|
|Here's the front view|