I know a guy who has been slowly automating very old food process equipment.
He makes peanut butter by the ton. Loading the hopper was quite tricky and getting up and checking a bit fraught. Knowing how much peanut butter is in the big vat thing once it is being stirred is quite hard too, and most sensors become less accurate once coated in peanut butter.
His ultrasound sensor (measuring the distance to the surface of the peanut butter) is a thing of beauty. He used Arduino.
You should tell him about pulsed coherent 60ghz radars from Sparkfun(based on the XM125 from acconeer), they may be able to work through peanut butter to find the level in the vat(they can see through walls).
