or a tapered mill bit. I'm in the process of trying to make the block thinner. As it is now, my block is a full one inch thick. I have two pieces of .25 inch Aluminum to try out. Think I'll use a piece of lexen for the jet or find a way to plug up a hose barb so that it tapers a bit and drill a 1/8 hole in the center. The end of the nozzel has to be 2 mm from the base with an extrusion from the top plate to fit in the recess of the bottom plate. The trick is to keep heated water from recycling back into the impingement.
Pic to help explain.
I'm thinking if I go to the .25 inch bottom plate I won't have to use my hacked job jet impingement like my first post above with a full .5 inch plate.