our props master thought this up for the house of cards we did close to what Prizm did:
Bottom row- each "triangle" was taped together at the top. and, through a tiny pin hole in the US bottom of the card, fishing line ran through it, knotted at both ends with the US end trailing to the ground with a little ring then resting on the ground.
For the "in between" of each row was a flat row of cards
second row-5th row: was just taped "triangles" with the in betweens rows flat.
we did this up til there were two "triangles" left with one card resting on top, so all that was left was the last "triangle", which the Max held in his hands, and every time he went to finish it, ended up talking more to Charlotte.
When the door slammed, he only had to twitch his foot slightly. Both feet were on the fishing line with one holding the ring in place (so it wouldn't just slip under his foot and not fall) and the other doing the twitching.
Also our Props Master thought to put a small version of a table runner underneath the cards, this helped keep the cards from accidentally falling, helped to hide the fishing line, and made easy cleanup for the end of the scene.)
The only thing that we had to do during tech was place two glow tape marks, showing where the actor had to put each foot when he sat down in the blackout.