The Handmade Film Institute has been working on creating a (relatively) non-toxic process that is just as effective and long-lived as commercial processes, but does not use the long-lived toxic chemicals (like Dichromate or even Hydroquinone) that form the basis of those commercial formulations. We, of course, are not the first to seek to do this, and our work certainly involves things that others have figured out. But we had some specific requirements that we wanted to meet, and have sought to codify recipes that meet these requirements.
The process described here involves a high-contrast, fast-acting developer that is long-lived and replenishable, which can be used instead of standard developers like D-97 and D-19. The principal attribute that this formula offers beyond other high-contrast caffenol formulations is that it has a preservative to prolong its useful life, and hence can be used, with replenishment, indefinitely, in the same manner as labs use D-97 in continuously replenished continuous process machines. For the individual, it means that you can mix up a batch and with proper storage be able to use it over and over again without needing to dispose of it. It is thus not only significantly less toxic in its formulation than conventional developers, it is also less of a burden on the environment in that there is much less disposal that needs to happen.
The recipes as presented have proven themselves over several thousands of feet of film, but are still undergoing some refinement, particularly as regards replenishment rates. We welcome any feedback from other filmmakers who work with these formulas!