The last two steps in your mash tun cooler construction involve connecting the ball valve to the drain, and connecting the drain tube to the ball valve.
Connect the clear tubing to the barbed end of the ball valve with a hose clamp, and tighten the hose clamp as far as you can.

Finally, attach the ball valve/drain tube to the pipe nipple on the outside of the cooler and you’re done with the mash tun cooler build!
Happy brewing!!!