My Deere dealer has a 3pt 4' brush. It's about 4'wx2'd and about 18" tall. It is full of stiff, vertical nylon line, like really thick trimmer string. Each line is 36" long and looped thru a couple holes in the top attachment plate, and somehow they are attached so as not to pop out. I haven't seen it in action, but the salesman showed me an area they used it on, and it looked pretty good. You gently lower the unit and drive forward, and the nylon lines comb the grass, pulling the gravel out and onto the drive. This was last spring. The unit is $1,000, but seems like you could fab one up in your shop for a fraction of that. Just need a source for the nylon line. Let me know if you are interested, I can see if they still have it, and maybe get some pics, or the manufacturers name and website if they have one. I think I'll do that anyway and post the info here. I'm sure lots of you would take a shot at throwing one together, and maybe selling one to me.....Serge.