What do you have Batman and Robin tethered to? That is precisely how I was planning to post mine!
Just tie a few knots in the top of the cord & then open the glass door on the detolf and close it with the knotted cord inside, it will hold the weight of the figures. Mine are still in the exact same position after 12 hours. 'Man, the lactic acid must be building up in their arms.
Oh, and I stuck a bit of Blu-Tac on the bottom of their feet to help adhere to the smooth glass.
+ use the Batarang holding hands.