The block would be 60mmx66mm solid copper. The shaded region would have clearance of 1mm between the top and the base. The rest of the channel would be 1/2" deep. Base thickness would be 1mm. The central barb itself would be encompasing the conical pins, causing a restricted jet flow over the core and around the pins. The shaded region would be an extrusion from the cap of the block, not the base of the block.
Let me know what you guys think. I'm testing the water with block designs. I'm going to have access to my school's cnc machine this summer.
Sorry for the poor quality picture also...
-Zoson