There is a board game in development that requires dropping 20 cardboard counters on a map from a height of 18 inches and then adjusting them into grids based on where they fell.

To paraphrase the iPhone commercials, is there a VASSAL app for that?

I think what you’d need to do is send the pieces to random locations,
except that a uniform distribution is probably not right for this. To
do it properly you’d need to write a custom trait.

Although from personal experience - those “drop from” mechanics NEVER produce a random distribution over a given area.

Typically, the dropper releases from at or near the center of the zone, and the likelihood that a piece lands in space ____ can be reasonably represented by concentric rings of decreasing probability.

So a truly random VASSAL solution (such as rolling for random x y coordinates as I suggested) would give very different results from the real world method.

My hunch is that this won’t give you the same distribution as dropping
a bunch of pieces, as you’re randomizing over a uniform distribution.
If you drop a handful of pieces, you’ll end up with more directly under
the point from which you dropped them and less as you radiate outward
from that point. To replicate that, you need something like a 2-D normal
distribution.

I’m not sure I understand the physics of this, but I’m not sure that a normal distribution is right for this. I would do some experiments. Why not do this repeatedly with differing numbers of counters (I think the number of counters dropped is going to change the distribution substantially)? I’m guessing that the angle from the centre will be uniformly distributed, so just record the deviation from the centre. If you had a graph of this, I’d be able to identify the distribution immediately.