Allow inputs that are not from the world or other factories

I’m building a space elevator factory and want to plan out the tree but want to hand feed the required inputs such as reinforced plates and rotors for smart plating required in phase 1 and so on. One limitation of the tool is we can only specify either raw resources (ores, oil, gases) from the world or outputs from other factories. For this factory, I’d just like to hand feed some inputs so I can see how long it would potentially take for the space elevator parts. Since only a specific number of outputs are required, I don’t want to make something permanent that depends on logistics from other factories.

Something like the screenshot below (ignore the red border :P)