I did mine in 3/4" Type L copper. From the compressor, I ran a vertical along the wall, then made 5 zig-zig rows coming down the wall. It was all pitched so the water would flow and not sit in the pipe.
You can kinda see it in the background here http://www.homestead.com/chuckthetruck/files/x7mb6_020.jpg

50'? Piece of cake.