I think you drill them then heat treat the steel to harden it. I’m no expert though.Probably easy enough to get the steel, but how do you drill the holes? Just curious.
You get to the point though of thinking is it worth the hassle? I’ve already had certain parts for the machine manufactured over the last ten years as the supply of parts dried up. The one off manufactured parts were actually cheaper than the genuine parts from the agent but my time spent on design and running about round machine shops or doing it myself was considerable.
This is a factor in deciding whether to carry on with beet or not. And presently I’m thinking not. Too much overhead for a smallish acreage.