How would you guys design cubes?

I’ve been thinking of that recently as I work on a module in which players are handed a set of 20 cubes they use–primarly–to activate an area (that’s an area-activation wargame, if you ask). Things I’d like to achieve:

- impose the cube limit;
- avoid map clutter.

Cubes initially are located in the pool, but they can be placed on the board and–occiasionally–removed from the play, permanently.

I’ve come up–theoretically–with a solution in which there are three GlobProp: # of cubes on the board, # of cubes in the dead pile, # of cubes in the pool, where all the numbers sum up to the limit. Each cube would have a layer, levels of which would represent number of cubes in the area (to avoid the clutter); module would not allow to increase the layer once # cubes on the board + # cubes in the dead pile == limit. The cube pool would be abstracted to a text label displaying number of remaining cubes.

Do you can think of any other viable designs?