I bought one of those plastic liner rinks. It has the form on the ends and you level it with snow.
Says it'lls work on anything that's not on a huge hill, put put snow on the one side to level it. Made sense and my backyard was pretty level. Buy it, set it up, pack snow against it, fill it was water and it was all evened out. Somehow come out the next morning (this was last winter and it was about -3 degrees out) and all the ice is to the right side. The ice was perfect on the right side, but the left has next to no ice on it, was like a little thing sheet that'd break if you walked on it. The rink was rather big and I couldn't build a platform for it due to too much snow, alot of the stores were closed, and it was cold and snowing like hell. Just waited for it to thaw and took it back.
We've got an outdoor rink almost no one uses about five minutes away that's of very good size, so I'll stick with that.