I don't stack cut very often. However, I have tried just about every method I have run across. For me, none of them works, as well as small dots of wood glue in the waste area. I clamp the pieces for 20-30 minutes and then cut the pattern. The layers never move, and there is no gap between the pieces. The cost is nearly zero.
This is not stack cutting, but it is something I do fairly often. I cut the pieces from thicker solid wood and then resaw the cut pieces on my bandsaw.
Here are some ornaments resawn from a piece of 3/4-inch stock.