hi Cathar and killernoodle!
ok, the holes in the pic are full of water so they dont look so deep ,but actually they are 3.5mm in a 4mm base
i managed to get the bottoms fairly flat (home made end mill, lol), but was careful not to get carried away when i saw what was happening to the underside of the base
holes are 1.8mm , tubes 1.25mm. i tried to optimise jet density, and kinetic energy, with a compromise as to machinability (60 holes is manageable, 300 is errrr, etc...)
no cfd unfortunately(!?)
anyways the end result is probably not far off from the original cascade, so hopefully results will follow likewise