The first thing I did was measure the bottom area of the cooler so I could design my manifold. Next I cut all the pieces and laid them out on the floor.
Then I test fitted it all together
I removed the drain valve from the cooler but left in the white rubber seal. Installed the nipple in the drain hole and put the flat rubber washer on the nipple then attached the copper adapter on the inside.
I put the 1/2" o-ring and zinc washer over the nipple on the outside and then put on the ball valve.
Because of the location of the drain hole I had to reverse the manifold and use a 45 degree 1/2" copper fitting to get the manifold to attach to the copper adapter.
I soldered the 45 degree to the adapter and the copper pipe to the 45 so It wont suck air when the liquid gets below its level.
The manifold is not soldered together so I can take it apart for cleaning.
Here is how it looks all put together.