Dui, ni shuo de dui
I have a similar issue, but mainly with aluminum. Most of the chattering occurs on the very last path, when it goes through the material.
I think this is a clamping issue: when the bit goes through the material, it tends to pull it up from the table, and I guess this creates the vibrations.
Maybe you could try to secure your plywood in the middle, by directly screwing it onto your waste board at several places. Should reduce your shattering.
Your model looks great, where did you find it?
One remark though:: it seems like you are wasting quite a lot of material while milling, try to better organize your parts before making a cut.