Next, I want to add an automatic mode to the code so that the machine can pump the ink around on its own by reading the sensors and switching the valves. 

The machine should be able to run on its own unattended without overflowing and flooding the bottom with ink.

To prevent this, it needs to be able to detect faults.

So I added a float switch to the vacuum tank for detecting an overflow of the system and turning off the machine in case of such a fault. I also want to add timeouts to the code to shut the machine down if an operation takes too long because something is wrong with the machine - like a valve not closing properly or so.

Here are some pictures of it: