I was lucky enough at one time to live close to a junk metal yard. i found some solid steel cut from 4" stock that was about 12-13" in diameter, made some great weights. I welded two together with a bracket to hang off the front of the tractor as well. It weighs about 200lbs or so. Its heavy, dropped it on my finger a month ago and it still hurts.
You might also want to consider making a weight box for the 3pt if you have access to a scrap yard, all you need is a few pieces of sheet steel, pins, concrete and a welder.
You might also want to consider making a weight box for the 3pt if you have access to a scrap yard, all you need is a few pieces of sheet steel, pins, concrete and a welder.