Looks like a good start and an interesting twist on the jet block base.
Two things I would note, you are going to have a serious restriction at the input triangle jet arrangement unless you taper them somewhat and the dimples you made in the copper base are angled and will probably create some dead spots.
I would use a X-acto knife or similar narrow blade (twirled in the holes) to taper them more so that the water is not impacting such a large flat area to get through.
Without tubes coming in from the jet side... I would not know the proper shape to maximize your turbulance. Anyone help out here? :shrug: