What drill are they to fit. Lots of different designs around that are aftermarket.
ThankyouContact needham ag in the US he actual is English and sends bits and pieces over here regularly to clients. But I doubt they will be 3’ - 4’ in diameter that’s tiny. May be that you need to find a local engineer with a profiler and a machining centre.
Just get some lazer cut .Thankyou
Laser cutting would be your cheapest option but as said 3-4 inch diameter will clog in moist soils and the bearing will be shot in no time being exposed to dirt all day. The needham version works very well on clay/high moisture situations call him he’s a very smart and friendly man. I’ve bought a pile of upgrades for my Deere drill and all have been worth the money. Often cheaper than original mother Deere. Not that that is hard.
would a straight disc on the one side of the press wheel say 10 mm deeper than the wheel shear the soil to let the press wheel push the slotThankyou I was toying with adding a closing wheel to my gd, bolting a bracket onto the rear wheels and angling a small spiked wheel. Hoping to crack the slots as even rolling after is only so good on heavy land