Automatically creates anything input! With assemblers, at least.
Has two constant inputs. The first requests each item by desired quantity. Said quantity is the MIN inventory required. Double that is the MAX inventory.
The other one assigns a priority on each item based on how far down the crafting tree it is. Priority 1 is raw inputs from an external belt, priority 2 can be crafted only from p1, p3 requires at least one p2, etc.
If any material goes below the MIN inventory, the system crafts an amount until it meets MAX.
The highest priority items are served first, to ensure both manual priority preferences (E.g., craft inserters before belts) and ensure that more inputs are created when needed.
As I get time, I plan on expanding this to include liquid crafting!