Container System:

Cards are not the only way to signal the need for production of a part; some other possible approaches are :

Container System

In this case an empty container on the factory floor visually signals the have to fill it. The amount of inventory is adjusted simply by adding or eliminating the containers.

Kanban Squares

Certain companies use spaces on the floor or on the table to recognize where the material should be stored. While the square is empty, like the one on the left, the supplying operations are authorized to generate; when the square is full, no parts are required.

Coloured Golf Balls

While a part utilized in a subassembly is down to its queue limit, the assembler rolls a coloured golf ball down a pipe to the replenishment centre. This tells the operator which part to make next.