So, I'm definitely into this idea of creating rather than expending mass amounts of money on a manufactured no-till drill. But the thing I can't get my head around is how to create a functional drill that moves the heavy amounts of residue (thick thatch that's needed to suppress weeds in an organic systems) aside or cutting into those layer prior to opening up that v-shaped furrow for the seed with your disc harrow blades. Would it be reasonable to you to weld a separate frame that contains arms for coulter blades to bolt into? Suppose you'd need to weight it down fairly well to allow those coulters to do their job...
Anyways, have you considered this sort of innovation for farmers who are seeding cover crops into crop stubble? My goal, for example, is to be seeding winter peas into fall-combined grain fields in Montana...
I have not given that much thought since I just made my drill as a one time project for my particular use. I only have to deal with fairly fine residue when I plant which is no problem. But I suspect that for heavy residue you would need to mimic standard no-till drill designs which use paired coulters slightly angled to simultaneously cut through residue and create a furrow. You would also need to use press wheels to close the furrows rather than the scraper blades I use which would clog with residue. Good luck,
Bill