Fusion Reactor Control Computer MK-I (also applies to other tiers): one machine handles both ordering and passive tutorials.

When you first start with fusion, it is often early LuV. At this stage, building even one fusion reactor is very time-consuming, and in some cases, such as when passively producing Liquid Europium, we need some Californium; without touching the passive input hatch, this can be rather troublesome. Here I offer an idea for everyone's reference: as soon as you order Californium, immediately have the machine stop the passive production of Liquid Europium, and as soon as the Californium is done, immediately start making Liquid Europium again, squeezing as much performance out of the machine as possible.

It is recommended to use an EV Quadruple Input Hatch, an ME Stocking Input Hatch, and spray paint.

The overall structure is relatively simple, as shown in the figure below. From left to right are an EV Quadruple Input Hatch covered with a Fluid Detector Cover, a Redstone Repeater, and an ME Stocking Input Hatch covered with a Machine Controller Cover. When an order is placed, fluid enters the EV Quadruple Input Hatch, the Fluid Detector Cover emits a signal, controlling the ME Stocking Input Hatch to stop, thereby interrupting the original passive Europium production process; after the order is completed, the Fluid Detector Cover does not emit a signal, and the ME Stocking Input Hatch turns on, thereby resuming passive Europium production.

A Redstone Repeater is absolutely necessary, because sometimes the order quantity is very small and the signal emitted by the Fluid Detection Cover is not enough. The chamber priority does not seem to work in the current version; the machine still prioritizes the previous recipe, so this solution was designed anyway.

Here, because I was too lazy to mark irrelevant liquids such as water one by one in the output hatches, I used the spray paint feature 'inputs of color A are preferentially output from color A' to restrict the output. The red box in the figure below shows the hatches I painted the same color.

If you have any ideas for improvement, please share them in the comments.