I would make them fairly small (personal pie-sized) and use a filling that doesn't need to be cooked in the oven to set. The main limiting factors, I think, would be structural integrity and heating the filling to the center. You could set it on a ring (like the rim of a spring-form pan) to support it better during cooking. Now, a four dimensional hyper pie, on the other hand...
If you’re not cooking the filling, then do a teflon ballon that you put the crust on. Cook. Remove balloon. Then pipe in ready to ready to set chocolate cream.