Someone recently asked me about representing flying figures on the game table. They were having trouble coming up with ways to inexpensively deal with showing various altitudes in three dimensions. My suggestion was picking up a package of pizza box supports. They can be used simply to represent being above the fray but can also be stacked, each one denoting ten feet in height, to deal with multi-layered combat in flight. One can get a bag of one hundred of them through Amazon for less than a sawbuck!