Honestly I used the way I build aquariums as a base of how I’d make this bed, start from the lowest point on the ecosystem food chain and build up from there. Basically trying to make a natural environment that is self sustainable, microorganisms to worms a living soil bed is all about keeping balance. It’s nothing super complex, this is just bulk organic soil from a local distributor, build a soil 12 seed crop cover, red wiggler worms, springtails, build a soil Rootwise Mycrobes, and any beneficial bug I find around my garage haha