Well i just got started on my second water block. i am not expecting great results but I connot get the idea out of my head.
The main channels in the top and bottom are 3/8" wide. The middlw three channels are 1/8" wide. I will connect the top and bottom tomorrow. That way there will be a consistant 3/8" flow through the block. And yes I know the fins will restrict flow but it will not be a lot. I am also going to mill off about 1/6" off the center 2 fins so water will not only go around them but also on top of them which will add a little more surface area and help with flow a little. I left the base at about 3/16" for now.
Here are some preliminary pics: