Stephen, I apologise for the late reply, some how I missed you response.
I first secure the figure to a first smaller box,I add foam pocorn all around and on top of figure,and tape the container shut.
I than get a larger box and pour a layor of foam popcorn on the bottom, next I put the small box containing the figure inside the larger box and pour foam popcorn all around it and on top.
So far, I haven't had any problems with this method.
Good luck and keep the great work.
Cheers,
Roc.