I doubts the claim about only being able to produce with a 3d printer. I can imagine easily making the layers in mass out of wood and sliding them through bandsaws to mass produce these.
You don't need 5 axes to machine what he machined.
It looks like you can do it with 3 (at least, my CNC seems to think it will do it).
4 at the worst if you want to spin it for some reason.
Truthfully, the problem they have is that it's still cheaper, easier, and more accurate to do this with a subtractive CNC machine.
This can't be done in a single setup on a 3-axis, its not xy-monotonic (there are overhangs). Theoretically you could do it on a 3 axis by manually remounting the piece at different angles, but it would be hundreds if not thousands of setups. 4 axis is definitely the practical minimum to machine it.
It looked like the the overhangs can be machined with a small rabbeting bit (remember that we can use more than just end mills :P), and like i said, both my pieces of HSM software seemed to think it wasn't trouble (IE the simulated finished piece is within 0.001).
You are right that in practice, you would likely want a 4th axis rather than messing around, but a 4 axis setup is just not a big deal (the 4th axis on my woodworking CNC cost < 4k)
You could not make it with a 3-axis CNC machine in one piece, but you could modify the design to make it possible without too much trouble. One way could be to make the base separately, and then insert the "blinds" that makes the digits separately.
