Base 10 blocks (units, rods, flats and cubes) are a widespread manipulative material for teaching place value.
However, piling rods on top of each other is not very stable, so it is not easy to build one single tower with all pieces that represent a number.
As an alternative, one can use flat pieces for rods, cubes and beyond, exploiting the fact that 10 is a triangular number.
Using this system, 9999 looks like this:
I would like to know whether this system has been described before.