I've also thought about your idea of having three layers, but more like the cascade.
So I thought about the cooper base (with the layout like discussed) and two layers of acrylic. The top layer will have the holes for mounting it on the mainboard and the inlet and outlet.
the second layer will be of acrylic too. under the inlet there is an open box with more jets than 7.
How thick should these two acrylic layers be, in order not to break and to seal properly.
I thought about having two o-rings like the cascade.....
please don't take the dimensions of the pic for granted
