I took what I could understand about mash tun manifolds and came up with this. I obviously haven't cleaned it or slotted it yet. Is this what you people are talking about?
There will clearly be deadspace at the bottom. I cut the manifold so it sits diagonally and the effluent pipe is perfectly flat. I could get it to sit on the bottom of the mash tun and put an elbow to the outlet, but either way I have deadspace.