I used CPVC for mine and made it into an 8 sided figure that just fits in my round cooler. I used wire drills to make the holes and then enlarged until I got a good flow rate without too many big drops in one place to create channeling. You could do the same with the copper (I'm assuming it's flexible tubing. If not, you just need a bunch of 45 degree elbows. I use several "s" hooks to hold the sparge arm above the mash.
I was actually thinking of building a rotating sparge arm with the copper I have laying around, but I don't know what to use to get a movable, yet watertight, fitting (something like the setup on a laundry sink lav?) Maybe someone here has an idea for that anc could post it?