[Puzzdre]

I need your help people!

situation:

I want to make a wblock with tools I have, so the only way is drilling the copper block.

The thickest piece of copper I could find is 10 mm.

The block will be drilled on my pillon drill.

I'm not making a great performer, just want to make it performs as best as can.

the tubing is 1/2", pump is micro Jet 200 Gph, Lancia prisma heater core.

I dont have that much copper to try everything that crosses my mind, so this is what I'm thinking:

No. 1. all holes equal, 3 mm dia, base thickness 3 mm, connecting channels 7 mm dia