At New England Ski areas in the 60's and on into the 70's, they used a piece of culvert pipe about 10 or 12 inches in diameter. They poured it full of concrete, put "Pins", Short pieces of bar stock or even re-bar sticking out of the center, then fabricated a big "Wye" shaped frame and pulled it along as a roller. It was highly effective and required no hydraulics. They were most often draged behind a Tucker. Cheap, easy to build, and effective.