I made mine a few years ago, mostly from stuff around the farm. To hold the scarifiers, I used two pieces of channel back to back with the space between them a little larger than the scarifier. I made mine too tight and had to shave a bit of each edge of the scarifier to get them in. The top and bottom of the scarifier holder is flat stock cut to length to space the scarifiers equally. I made fancy self locking pins up to hold the scarifier at desired height, that was a waste of time, lost a couple of them. Now just have round stock with a hole drilled in each end and use R-Pins, lot simpler and works better. To hold the pins, I found a piece of angle iron that they fit nicey into and cut into one inch pieces.
I put the 2" square stock running back from the three point hitch too close to where the scarifier is, not enough room for R-Pin between it and scarifier. I mounted receivers on these members for gauge wheels but have use them more for receiver hitches to haul trailer around than gauge wheels.
Go to your highway department or anyone else who has graders and ask for a couple of used cutting edges. These are usually scrap, usless they have changed over to the carbide tipped ones. They go through the old style ones by the truck load. There is plenty meat left on them for home use. You will have to cut them to lenght. I mounted two cutting edges on mine, back to back. One for dragging, and one for pushing. When cutting to length, bolt them together so the holes will line up when your finished and then just bolt them through the back. If they are in a good mood, ask for half a dozen of the proper bolts, they're called plough bolts. They go through them by the bucket full.
I made up a set of plans before construction, I'll see if I can find them.
